For what it's worth, I think this tickles my sensawunda in the same way as having the HoS in India be its High Judge, or the Ooni of Ife being the HoS of Oyo, or even the International Congo's status under the Court of Arbitration.
It would certainly be one way to portray a successful strategy to deal with the tension between Han and non-Han in Qing and post-Qing China - that Qing efforts at defusing, wikipedia says, lead to the earliest incarnations of the concept of a Zhonghua minzu. You could present it as a package deal, too - reach out to ethnic Chinese abroad, while creating an acceptable framework for closer integration between Han and non-Han at home.
The more I think about this, the more I think it's likely to happen. No one wants the Qing back, no one wants to give the Ma clique that much power again, and the republican interregnum is remembered as a period of instability and unrest - so after a period of regency when no one can come up with a better answer, why not the Duke of Yen? He'd be somewhat like the Japanese emperor under the 1947 constitution: a purely ceremonial head of state, not even the nominal chief executive, but a spiritual and cultural symbol of the nation. He's also someone that nearly everyone would respect - even the Chinese Muslims
had Confucian influences by the 18th century.
I could see this taking place in the middle to late 1950s.
Oil can be a curse, or at least a mixed blessing. You have actually addressed that point already, but it is interesting to see an important Great Power controlling a large part of the world's oil supplies, something that only marginally happened IOTL (with the US). TTL is also better equipped to deal with the cursing aspects of oil extraction in order to minimize them, although I don't think they'd disappear. For instance, Japan is going to be VERY interested in the security of Nusantara.
They won't disappear - a couple of updates from now, we'll see more of the difficulties that oil politics are causing the Ottomans - but on the other hand, more of the oil resources are in reasonably strong states that have methods of resolving disputes short of civil war. There are fewer potential Niger Deltas - hell, in TTL, the Niger Delta won't be a Niger Delta, and I'd guess that the oil there will be found sometime in the 1940s.
The Ottoman-Indian relationships will also be very interesting ITTL in the next decades. India is re-industrializing at a rapid pace, and this means she will need a LOT of Ottoman or Persian oil.
That's potentially a two-edged sword, though - neither the Ottomans nor Persia will want to lose a customer as big as India. Oil politics should, at the very least, lead to some interesting moments.
I am not sure that Ethiopia and South Africa are too small to aspire to Great Power status. They are both pretty large, and they have both populations in the same order of magintude as Brazil or Metropolitan Britain at this point. (I would guess 25-30 million for Ethiopia, which is actually a little low for a real Power, and possibly a little more for South Africa, which has however, an incredible amount of resoures to compensate; the Ottoman Empire, for comparison, is probably in the 50-60 million range now, and likely to be increasing quickly- Metrpolitan France and Britain are probably about there too).
That's about right. Ethiopia's possessions in southern Sudan, Eritrea and Somalia, and the fact that it's currently on the steep part of the demographic-shift curve, should get it to around 30 million. Once it picks up the Yemeni states
de jure, that will add another five million. That's certainly enough to make it a dominant power in East Africa and a player in Arabia, but I'm not sure it's big enough to compete on a world scale. A
really big country with a developing economy, like India or China, can become a great power; a medium-sized developing country, probably not.
The combined population of South Africa, Lesotho, Swaziland, Botswana and Zimbabwe in the early 1950s OTL was ~18 million; add the *Namibian territories, Mutapa and TTL's greater prosperity, and the South African Union is probably in the low twenties. Again, that's regional-power size, at least for the time being; the fact that it's a British dominion would also make independent great-power status complicated.
Brazil's probably at 70 million and has enormous resources, but still has a developing economy, albeit a more prosperous one than it had at this time in OTL. The Ottoman Empire has about 60 million and is considerably richer, not to mention the intangibles that follow from the Sultan's position as Caliph.
Say 55 million for Britain without WW2, and about the same for France without the war and with more immigration - add another 10 million for the overseas departments. Germany's probably pushing 90 million by now.
It occurs to me that the idea of cultural minorities within a nation, such as the Roma or the Jewish diaspora as mentioned earlier, may be a definition applied much more broadly throughout the world as time goes on. In particular, in past discussions we've mentioned that America will have a sense of continuity with the 1800's in the sense that minority groups will have greater integrity of old country linguistic and cultural heritage even within the US framework. With 11,000 members, I'm wondering if it's not inconceivable that the diaspora of various nations ends up sending one or more representatives to the Consistory as cultural interest representatives. These representatives might defer to the State's representatives for most times, or they may be in a more terse relationship, but it would certainly put a very different spin on how cultural matters, domestic and international, are handled. For some odd reason, I'm imagining a "German diaspora" representative from the US alongside representatives of African American, Native American, and so on.
It seems pretty out there, but, again, 11 freaking thousand.
I can easily see Native Nations having representation (more probably as separate entities, not a single Native representative). For diaspora communities, it is more complicated; regionally strong communities may get representation, but institutionalizing the "American Germans" as an internationally recognized entity as such would be such a gigantic headache that nobody would probably want it if politically possible.
I think that any such entity should probably have a fairly marked territiorial connotation to be viable in most cases. However, I agree that 11 thousand is a lot. To be fair, some my guesses on the future of Italy ITTL might lead that peninsula alone to yield some about 200, if not more, members, but this is extremely tentative and Jonathan's plans may be very different.
I won't get too detailed about my plans now, because doing so would reveal a bit too much of the late 20th century including parts that I'm not yet certain about. As a rough outline, though, many of the Consistory's members in 2015 would be considered first-order administrative divisions in OTL: autonomous provinces or even cities. Remember that sovereignty in TTL's present will be seen as a continuum, and that as in the medieval era, the fact of owing allegiance to a higher-level entity won't be a bar to engaging in international relations. A great deal will depend on the constitutional arrangements that each state has with its subdivisions, and some countries will be more unitary than others, but I'd expect at least a couple thousand members to fall in this category.
Then you've got the international agencies and quangos, and man, will they proliferate during the late 20th century, especially those that are regional rather than global in scope. After that, special territories that have Legatum or similar status, and non-territorial collectives. The last category is where there could be representatives of national minorities or diasporas - and as you both point out, there will be debate over what constitutes a sufficiently cohesive cultural group as well as internal differences within these groups, but the same is true of states, and that's just part of the fun! Much will depend on whether the groups in question want international representation and whether they can convince the relevant authorities that they're entitled to it. German-Americans, maybe not, but a culturally significant regional German community (on the one hand) or the world German diaspora (on the other), maybe so.
There will be plenty of NGOs in the Consistory too, but even in TTL, those will be observers rather than voting members - the qualification for membership will be a legal right to enter into international agreements on at least one subject.
I'm vaguely interested in writing about the Wisconsinite Yankee v. German divide and tying it into the Consistory's development, especially considering I've got half of it written from my abandoned guest update from a ways back.
Now
this I'd like to see.
In any case, I doubt having some type of anti-fraud measures against fake halal foods being sold (ie., some type of halal certification scheme) is going to be particularly controversial, except perhaps among some really hardline "withdraw from the state" types. But they're probably not going to have a lot of traction, especially if there are any incidents of that sort of fraud being perpetrated (whether on purpose or through mere negligence).
However, you guys convinced me: an authority, or several ones, entitled to issue "halal" labels on foods and other things is quite possible ITTL.
My guess is that it will be more of a clearinghouse for authorities, along with export regulations designed to ensure that all halal-marketed merchandise is certified (either by a national authority or a private one) and that the certifying authority is disclosed so that the purchaser can decide whether to trust it. I doubt that the international community would establish an authority under its own auspices, because that would raise issues of sectarian preference, although regions where Islamic practice is fairly uniform might have them. The same could be true of kosher food, although the "two Jews, three opinions" doctrine applies as much to kashruth as to anything else.
But by and large I wouldn't want to see a storyline thread stripped of the comments. Sometimes people go off on tangents of great interest to them but not advancing the story much

o) or get into fights, or try bullying an author into more updates by throwing virtual rancid food at them.

But generally speaking, the logic of the timeline works its way into the dialectic of the comments; people are praising, suggesting, and fighting
about the ATL. I wouldn't like to miss that, even on an old story thread that ended years ago before I found it.
Definitely not. As I've said before, one of my favorite things about this project is the conversations it's engendered - I've learned a great deal from them, and been challenged to broaden my horizons.