Which leads towards some form of compromise that somehow suits both parties because the effort required to win the war will likely have the same outcome.Thing is Putin can't afford to lose this war, cause this would be end of him. Also they gone too far, its too late (from their point of view) to just pick up and leave, admit of defeat would completely destroy their geopolitical standing among countries that sympathize with them and dislike Americans (China, India most importantly).
I don't think they will quit on their own, only real disastrous and complete military defeat (that would probably end with coup and Putin assassination) will lead to it, and until/if that happen, gonna still take titanic effort and a lot of bloodshed.
Also i have no doubt that China secretly support and supply them, its in their geopolitical interest to keep Russia afloat.
While currently unpalatable to both parties, a negotiated settlement is the likely outcome. Putin has bet his economy on the west losing interest in this war.
Unfortunately for him, this now looks more and more unlikely, which puts his weakened economy (9th by GDP) versus a financially strong alliance of nations.
In terms of Chinese support, of course there'll be some support, but this is itself short-sighted as it will ultimately come at other forms of compromise.
Does Putin want to become reliant on China?