[int_19h]

The problem is that Russia has succeeded in settling many of its colonized territories such that natives are minorities in most of their titular region. Consider Buryatia for a prominent example - Buryats have been used as Russian shock troops in Ukraine since 2015 (Debaltsevo), yet population of the republic is only 44% Buryat but 53% Russian. On top of that, much of the native population is culturally Russified.

Tuva and ethnic republics of the Caucasus are where the natives have majorities that mostly retain their separate cultural and ethnic identity, so if something does fall apart, I would expect it to happen there.