NATO may continue to exist on paper, but in the real world, it is as dead as a doornail. Why? Because the whole point of it is to use the American military to prevent Russian aggression against fellow liberal democracies, but Trump despises liberal democracy and thinks Russian aggression is just a normal fact of life. No one seriously believes American security guarantees can be relied upon at this point. Then what?
The French have a bomb, but the far right is likely to win the next presidential election, and it has little use for NATO. The UK also has nuclear weapons, but it isn’t even part of the EU, and the far right may win the next election there, too. The burden of protecting Europe from the Russians, therefore, will fall on the Germans.
Rebuilding a powerful conventional German military will be a slow and expensive process. The short cut would be to build a bomb. Given Germany’s, shall we say, awkward recent history, you would expect Putin to threaten a preemptive attack with both conventional and nuclear arms when he finds out about it. That’s when events in Europe start getting really interesting.