I believe this is about saving face, Russia can’t allow Ukraine to leave without something in return, especially, The Crimea, that if not for Khrushchev trying to make nice with the Ukrainian subjects he ruled over at Stalin’s behest, would not have even belonged to it in the first place.
Best case scenario a new deal will be worked out allowing Ukraine to join EU/NATO in exchange for ceding The Crimea back to Russia.
Now if they can’t make that deal, we’ve got problems.
I could see that; Russia gets the Crimean Peninsula, yeah....Ukraine gets a little butthurt, but as a consolation prize, they get to join up with the EU and NATO.
Crimea is Russia’s #1 concern; I doubt they care all that much about the rest of Ukraine, beyond lip service. But Crimea is do-or-die for Russia.
And like you said, if that deal can’t be made, then look out. That’s when TSHTF.
Remember what happened in Egypt. If Putin can keep up the pressure without allowing the situation to become a hot conflict he can just wait for the EU and IMF to very soon dismantle what is left of the Ukrainian economy. (They have done such a great job with Greece, Spain, Hungary etc etc.) Eventually there will be a new upheaval and that will be that.....
If the Ukrainians are foolish enough to give their sovereignty away to the EU that’s their business. I don’t want Ukraine joining NATO. That’s writing a check we can’t afford to cash.
Why would Putin ever agree to that? The deal offers him nothing, as he already has the Crimea. And I don't think Putin will ever allow what's left of the Ukraine to join NATO. No more than we would have allowed Mexico to join the Warsaw Pact.
So we've got problems.