Would the house of Romanov be able to make needed reforms?
Nicky certainly wouldn't. With a convenient assasination, I can see Grand Duke Michael establishing a proper bourgoise democracy in Russia with the Octobrists and Kadets. However long that lasted, it would last longer than the contradictory "system" of 1914.
I think that with quite a lot of luck on the part of the Romanovs, Russia could reform itself into some sort of constitutional monarchy eventually. But not all the people who could gain control of the state would necessarily abolish the now-powerless monarchy, which brings me to...
If not what replaces it, or is it able to cling on while Russia becomes ever more of a basket case.
I can see:
- *Fascism put in place by Black Hundredists and ambitious army officers with the connivance of the church, with Yellow Shirts, Okhrana, socialists off to Siberia, Jew-baiting, militarism, national chauvinism, you know the drill. That might happen in a quiet putsch if a constitutional or democratic regime was inclining too far to the left; or a sufficiently ruthless Tsar might impose it from the top, although personally I think the stuffed-shirt Nicholas II and his potential heirs are too late for that. You need someone with mojo. EdT uses Grand Duke Sergei in his spiffing TL.
- Revolution. Another *1905 isn't inevitable (nothing is), but it's neither imposssible nor doomed. Gaps between haves and have-nots in late imperial Russia were gigantic. Have Nicholas' regime continye, with all its incompetence and schizophrenia, and the middle classes that the October Manifesto bought off may turn against the government. Once the army are sufficiently fed up with the government as well, all it takes is a nudge.
This is unlikely to result in social-revolutionary Russia (to say nothing of Bolshevist Russia) without a war to create the necessary number of "peasants in uniform" and requisit social breakdown. I see something more like the Provisional Government, only less, you know, fucked.
- Succesful reform. Basically, this means that a competent tsar comes along and gets Russia using reform to broadly the place it would have been in the previous scenario: a parliament which isn't completely useless, some sort of executive responsibility, and power in the state broadly belonging to the middle classes.
What would Russian federalism likely look like if it comes into being at all?
*Fascists, of course, aren't going to divide Holy Mother Russia. For the others, I see it more as a gaggle of autonomies (like those briefly enjoyed by Latvia and Estonia) for the peripheral peoples. Turkestan was acknowledged as a colony (it didn't vote for the later Dumas), but the Baltic and Caucasian governorates could get autonomy. Whereas a republic - even a reformed monarchy - might be willing to tolerate Ukrainian language and culture, I don't see a territorial autonomy for Ukraine, which is what really turns "empire with amny autonomous bits" to "federal empire".
So, broadly, where the necessary middle-class exists to set up a regime along the same lines as the central one, autonomy: that's Estonia, Latvia, Georgia, Armenia. Azerbaijan, Besserabia, and Lithuania are much less certain.
Finland was already a state-within-a-state, and that's where I see Poland going in any remotely federal scenario.
How would Russification develop?
Ukrainian will end up like Scots: in one register or another, more mixed with standard Russian or less, it's the spoken language of Ukraine, and written fairly often to make a point; but all the commercial life and administration, most of the intellectual life, and the existence of the upper and middle classes takes place in Russian.
Ukraine doesn't have any ancient kingdoms, kirks, seperate legal traditions, etcetera, so this pretty much does in Ukrainian
nationalism as opposed to Ukrainian folklore enthusiasm. As Ukraine, so Belarus, but more.
Russian will be a widely spoken language among the educated in the Caucasus, with big Russian administrative communities in some cities, but won't budge the peasant language an inch. Baku was a melting pot already, so no change there. The people of the north Caucasus, though, may shrink to insignificance.
I don't see the Baltic people settled on an enormous scale. Soviet migration after the war had to do with the ports, a labour shortage, and the necessity of rebuilding. Russia now has more people, no devestation, and a mostly southern-orientated trade network.
There were quite big Russian communities in Riga and Tallinn in 1914, and as in every major imperial city I see them staying, but I don't think the native language will be displaced in the countryside - even if, weith urbanisation, the Russian-speakers become an appreciable portion of the population.
Actually, for physical Russian/Slavic settlement threatening the native population, I'd look at the Kazakh steppe...