I wish I believed that. His credibility depends entirely on his ability to threaten (to poison his opponents, to flatten cities). He's a strong man, and he can't afford to be seen to back down.

Here's the only off-ramp I can see working:

"Mr. Putin, you can keep your yachts and your offshore wealth; you won't be pursued for warcrimes. But you must exile yourself from Russia, and never darken the world stage again."

I don't think Putin would accept that deal; he'd rather go down with his ship. He thinks he's Peter The Great.