....I tend to think of history as the sum of people acting in concert - great men and women do exist, but they are little without a foundation on which to stand. The actions of the colonized peoples are part of the history of their empires. And in TTL, the colonies are ideologically dynamic, and the great powers are fighting a war which they're less prepared for than OTL's Great War and for which they need the colonies' manpower and logistical support much more. This gives the colonized peoples more leverage - a chance to effect asymmetric change within the imperial system, if you will - and many of them are taking that chance.
A beautifully stated and succinct view of history, Jonathan!
When I was pursuing a formal BA in History in the later 1990s I was exposed to the phase of the "culture wars" going on then in the USA, where Republicans under the wing of the then only recently gone elder Bush Administration were giving firepower to the general conservative backlash against "history from below;" one of their champions (Gertrude Himmelfarb, IIRC) described the various ethnic, feminist and so on movements as "history with the politics left out."

Implying of course that real politics, the politics that matters, is a matter of a handful of high roller power players moving us all around like chess pieces. One thing your writing in general does is highlight the way these power moves propagate "down" to very ordinary people. Right from the beginning I was wowed by the feminist aspects of West African Islam as you showed it, with the jajils and so on.
Actually, to paraphrase Aristotle in a less sexist way, human beings are political animals, and if you do history from below right, everything we do on every level is shot full of politics, starting with nuclear families. Without the social cohesion that comes from politics writ large being writ small as well, there would be no "chess pieces" and all the lines on the map would be written in sand, with random winds erasing them instantly.
It just feels incredible... and yet somehow right that this is right path of the Philippines. Given how strong the Philippine experience with American rule is despite just lasting practically between 30-40 years; you just created a different Philippines and am I right that this is still TTL's Asia's first independent republic?
I wonder if you can still have a United States looking for some small scale imperialism and see the Philippines as some Asian gateway and turn it into some security/economic protectorate of sorts. I am actually hoping for some Thomasites arriving and introduce English as a medium of communication for TTL's Filipinos, just with more Spanish speakers lingering this time rather than it's almost total disappearance here in OTL. ...
I've actually championed that sort of thing across many timelines and I certainly think we should have done that OTL (then it wouldn't be of course

) Instead of grand imperial ambitions founded on contempt for "new-caught, half-taught peoples, half-devil and half-child" to "Christianize and civilize" (ie, trying to grab some more chess pieces to mold as we would) the Philippine venture had been managed as support for an independent Philippines with us asking for no more than naval basing rights at Manila, it could have come across as a win-win deal; not only would the Filipinos acquire a richer patron nation to trade with, but our base there would be a tripwire serving notice to any other imperial power that messing with the sovereign Philippines would draw suspicious American attention. Might have been beautiful...
But as with every other scheme of the ambitious American imperialists of OTL, it's been neatly scuppered here!

The Yank impies have shown their hand in Mexico, alienating a movement there with many broad similarities to the socio-political makeup of the Filipino rising. They are bogged down with no money to build and deploy a conquering fleet and the political consensus that permitted the ill-advised Latin American mess is eroding fast, undermining imperialists in general and reviving the sentiments of the old Peace Party.
I'd have to check the exact timing to see which comes first, the Spanish crackdown in the Philippines or the American invasion of Mexico, but even if these Asian events started first, any American envoys who showed up to chat up the Filipinos would probably disclose a lean and hungry look that would put them off--they know that look.
If the Philippines need patrons, they know they'd better shop carefully. The British (if the Filipinos have no premonition of what is coming in London, or the stomach to look at India or the new regime in Indochina) already have plenty of choice possessions in Asia and won't seem particularly appealing. The French might not look so bad except I'm sure their trying to build up a suitable naval power to get the job done for the Filipinos would set off all manner of alarm bells in Europe. Maybe they can deal with the Germans, or simultaneously intrigue with both Japan and Russia...
Or just take a page from the Hawaiian book and play them all off against each other round robin. The Filipinos are better off than the Hawaiians; the latter owed their salvation from Yankee acquisition to the joint help of two belligerent powers, who in the middle of fighting each other could agree they didn't want to see the Yankees just sleaze up and take a plum colony for cheap while they were bleeding each other so expensively for theirs. The Hawaiians alone couldn't have done it. The Filipinos on the other hand are a much stronger force in being for any arrogant conqueror to deal with, as the OTL US Army and Marines were to discover so unpleasantly.

So if the Hawaiians can do it it ought to be a cinch for them.
Good points all. I was just running some brief thoughts on where it may end up. As you say, there are other likely outcomes too. The muscular military is likely. I wonder if a dispersed country like Australasia would be prone to coups. It would seem unlikely a coup plotter could have any real hope of securing everything. The ATL state will not be a Primate City kind of country, where capturing the capital/main city wins the game, like say Argentina.
Yeah. If there were civil disturbances, I'd expect them to be at the state level- ATL Mannix marching Catholic unionists past the Melbourne parliament while it debates a resolution on the Irish question, Labour leaders in Perth having their heads broken by mining company thugs. That type of thing.
I wondered where all this "white colonies in chaos" premonitions were coming from and then thought twice; I really don't know much about British 19th century settler colonies after all!
But from my Yankee perspective, they were and are basically British North America: The Next Generation, especially Australia. We certainly had our secessionist crises but these were about some very deep issues of the national constitution (lower case, referring not to an organizing document but more the sense the word had in the 18th century--the nuts and bolts of how America normally ran). And just a couple; on the whole, most of the time USAians (the dominant Anglo ones anyway) had little interest in the idea of cutting loose.
I'd think the same logic would serve to hold Australasia together. What would be the nature of conflict between settlers in New Zealand versus New South Wales that couldn't be patched over by federal politics? The positive value of being part of a large power composed of people basically similar to themselves would outweigh any fleeting advantage of local sovereignty I'd think.
As for the other sorts of troubles you all see ahead--they look awfully American to me!

The solutions might be no prettier than the OTL USA ones, but by the same token no uglier either.
The spiritual conflict of Australasia I'd foresee is basically an echo of the deep US one, the whole "revolutionary freedom" paradigm versus a real foundation on slavery and ruthless conquest of other people's homes. The Aussie version would be milder on the oppressive sides--the Aboriginals were too easy to push aside, whereas the Maori OTL cut deals with the colonists that Native Americans could only envy. And the other subject peoples will be the native Islanders of the Pacific that the British took from the French and consolidated with their own former acquisitions there and wrapped up in a gift package to hand to the Australasians, under the impression these were just another branch of the Empire after all. The white Australians and New Zealanders didn't seek them out of manifest destiny, just followed orders from London. So a lot less guilt all around--depending on how they handle these Polynesians and others henceforth. On the other hand, to this day Australia and New Zealand OTL are a lot more politically leftist than the USA and this reflects the combination of prison colony origin of some settlers with the general nature of the politicalization of British working class emigrants in the 19th century. OTL Australians danced in the streets on hearing the news of the Bolshevik Revolution, or so I've read, and here too I expect a pretty radical sensibility that might make shedding ties to London easier for them--but make the moral dilemmas of the likely racist shenanigans soon to ensue under their independent rule sting more sharply on their more revolutionary consciences.
I honestly don't see why you'd fear a greater likelihood of military juntas and the like than the USA should worry about! A Bolshevik type thing seems more likely to me, and that seems pretty far-fetched. (That's the type of thing that might split the Federation too. But I don't see it actually happening either--just maybe being more feared by the more conservative Aussies than OTL).
Well, I'm no Australian or New Zealander and might be way out of line. Canada, I certainly want to wait and see what Jonathan does with it! Who does this leave?
South Africa of course! With the hard lines of racial apartheid being blurred as they have been here, South Africa seems set for a quite different trajectory than OTL. Freed of their "laager" fortress mentality the white Afrikaaners blur into the "Coloured" ones (as OTL official Apartheid defined them, that is people of mixed Euro-African blood and culture) who have ties to the African natives; Anglo colonists have to insert themselves somewhere in this much more open and complex sprawl of cultural influence. The London regime is going to be very confused indeed trying to pull strings there! If there is a general secession, South Africa is in an interesting position. The angry British colonialists will find them a nearer target for punitive expeditions than Australasia, but the Afrikaaners have some experience resisting overseas domination and they can find allies--the Germans for instance might love to see their formal possessions in southern Africa multiplied tenfold (in value and population) and suitably disgruntled Anglo colonists might not mind the switch, as long as Berlin understands the importance of "ruling" with a very light hand. Or just accepts them as a soft power client/ally--the Boers after all have an independent streak.
If they don't slip into the bad habits of white supremacy, the soft power of an independent South Africa would be considerable; their influence will spread north until they run up against hard boundaries of other territories run well and with the locals having no interest--even there, the better run Central African polities can be wooed with trade and mutual development schemes.
If SA does split off from London I don't know how attractive it will be for British emigrants after that, but it would surely attract some from all over Europe, particularly Germans and Dutch and so forth to be sure. But the African majority will be increasingly assertive.
I see little reason for it to break up into little bits either. I suspect both South Africa and Australasia are already big and strong enough to do well on their own, without falling apart or under some strongman dictactorship.