I also think that military exhaustion on part of Russia seems like a highly unlikely scenario at this point. Also, I would be shocked if China didn't end up stepping in if it came to that. Losing Russia as a shield in the west would be absolutely catastrophic for China.

I also don't see the dynamics for any sort of Euromaidan in Russia. Ukraine was in a completely different situation economically and politically when the coup happened. In fact, three years of war facilitated purging any real dissent within Russia. A great illustration of that was the whole Prigozhin mutiny where everyone immediately declared their support for the government. It's also notable that public sector plays a dominant role in Russian economy now, so the power of the oligarchs is much diminished from the peak in the 90s.