Do you really see that happening here? It seems at this point, the best Ukraine can hope for, is giving the eastern half of Ukraine autonomy, and try to restore civil relations. Hopefully, the eastern areas will then reject Russian rule.
Hard to know for sure whether Russia is truly democratic. If it is, Putin would be committing electoral suicide by adding 50m Ukrainians who don't want to be part of Russia. It would be as if the GOP decided to add Mexico to the union by coercive means.