I think some people might be getting a bit overoptimistic.
As excellent as Ukraine's been at holding off the Russians, they're still outnumbered and outgunned. They've also had the advantage of defending for most of the invasion. Their counterattacks have gained ground, but pushing the Russians out of the country will be a big undertaking, especially in the separatists areas which have basically devolved into trench warfare. I also haven't seen much of Ukraine's armored and mechanized brigades, which would be important for any rapid offensive, and get the feeling they might've taken a beating blunting the initial Russian attack. Retaking Crimea and all else might be too much of a stretch.
I hope I'm wrong, though.