“If Ukrainian nationalists insist on having it their way, they may be left with half a country and they’ve already lost, it appears, the Crimea.”
Half a country is better than no country.
Obviously, the New Ukraine has to deal with the fact that a single largest ethnic minority in their country is Russian speakers. And we have a large ethnic minority that is Spanish speakers. So? How does that impact the issues of national sovereignty?
The Russian Federation has ethnic minorities all over the place, by the way. Putin just opened the door for the dissolution of the RF if the separatist logic is to prevail.