I still don't know why Russia wanted an East v West proxy war but at this point, they're seriously in the hole. Their economy is tanked and it won't get better until the sanctions are removed. Putin has gotten some short term gains in nationalistic popularity, but has alienated his closest neighbor permanently and pushed eastern Europe even further away. I just don't know what he bought with what he's spent.
The Ukrainian revolt this past spring was economically motivated. The Ukrainian economy was in the shitter and people got really tired of it. The more damage that Putin self-inflicts on Russia's economy, the more he risks of that happening in Russia as well. Any further direct involvement in the Ukraine will only strap the economy more (wars aren't cheap) and incur far deeper economic isolation. Abandoning the rebels in Eastern Ukraine puts him on track to resolve the sanctions, but the Ukrainians will eventually put down the rebels with economic help from the West. Putin will lose the pro-Russian people sympathy and affection he has gained by 'standing up' for the Russian population in the Ukraine. He won't be remembered for saving the Russians in the Ukraine but abandoning them.
All the while, Russia falls further behind the rest of the world (East and West) economically and militarily.