The proposal would save face for Putin. He would be able to boast to the Russian people that he got the US out of Europe.

NATO would be replaced by a European alliance. With Ukraine in the alliance, it would be formidable force. Trump is already talking about leaving NATO. He also seems friendly towards Putin. The UK and France have nuclear weapons. The US won’t have troops or equipment stationed in Europe, but it can join the fight with Europe if Russian invades.