A democratic referendum about the status of crimea was from the beginning the plan of the pro-russian government of crimea. The referendum is underway, it will already happen in March.
I don't know why you bring up communism, all countries involved are capitalist countries. I don't think there are any communist states left in the world, maybe cuba, but I'm not sure.
Theres amix of communism with capitalism in Russia, China and north korea. All of them still have dictatorships in their own way. If Russia was a proper democracy, this wouldnt be as much of a problem, as we would know that theres no way Putin wouldnt have dreams of grandeur for sure.
Theres a problem with referendum option. Who is gonna organise it? Russia certainly doesnt have the credability for it. They will cheat for sure. So, ukranian authorities have to do it. Will Russia retreat to let that happen? Somehow i doubt it.