I don’t think that it’s even necessary for the US to pull out of NATO. Trump1 mentioned that the US may not react if Russia invades a NATO member. That’s enough to damage the central promise of NATO. Voting for Trump2 is the end of it.
Unfortunately this means that Europe has to be able to defend itself by itself.
Unfortunately that that means giving even more money/power to the military industrial complex and to open the door for future military conflicts with the US.