It won't lose, not enough to make them reverse course like they did in Afghanistan.

Even if Ukraine looses Donbass, "something something holding back the Russian horde" and "something the long-term victory is inevitable", and "won the argument". Whatever stupid cope.

Russia isn't going to install a puppet government that can control Western Ukraine, so we get stuck with the Left explaining how they're not retarded for blowing out all of our money out their own asses to fund their own pocketbooks and domestic political campaigns with stolen war-profiteering money, all so that China can benefit more than anyone.

Hell, they'll start another war somewhere else to cover over their loses in Ukraine if they need to.