If that deal is now struck...
A rotten deal for Russia, but Putin can sell it to his people as success which, in some ways, it is. He has "liberated" the Russian sector and created a defensive buffer on his western border.
For Ukraine it would be a humiliation and one hard to sell. Greater security, perhaps, as Putin would not dare come back for more.
For the West, almost total success. Return to normal trading, a seasoned domestic military better adapted to modern warfare (without the loss of a man) and an adversary back in its box for generations.