There is a large amount of people that believe that Russia can't keep the war mobilization for a long time, for economical and political reasons. If that is the case, Ukraine is on the road to prevail.

Personally I don't know the region to get to form my own opinion. Does Russia has any powerful separatist movement? Can public opinion impact the government? Can the west actually harm the Puttin supporting elite enough to divide them? Those are all relevant and I don't know the anwser to any of them.