I'd bet a bunch of money on Russia backstabbing China if Trump can offer Russia full and permanent US recognition of annexed Ukraine as Russian territory.
1. What would Russia backstab China on? We give them what they need; they give us what they can.
2. There are so many hurdles to making that recognition possible that it just won't happen. There is bipartisan support for Ukraine in the US; American media blew it up as a hill to die on. He won't get it passed in the House and Congress regardless the composition.
3. The backlash in Europe would be fantastic to behold. Countries like Germany, France, the UK, Poland, have been conned by America into throwing their own countries under the bus for Ukraine. They were told that this is a life or death fight for democracy and freedom. Now, in worse shape than they've ever been since WWII, they watch the US sign Ukraine away? I'd love to see that.
4. American instability with 4 year elections swinging the national identity wildly means that even if Trump were able to make this offer to Putin, it is very possible the Putin would go to Xi and say, "Let's put on a show and rob this orange bastard of every cent we can while he's in office. 4 years later, we stand together again."
