If NATO would die by the US leaving, then maybe it should. But it seems to me that it should still be able to function without the US, and SHOULD if at all possible.
It seems like a no-brainer to just cut out the Americans from the organization but there's certainly a lot of organizational infrastructure that depends on American technology and resources.
we're just putting trump on the naughty step for 4 years and beefing up european military
Remember that this is the second time Trump is elected, and nothing at all guarantees that another Trump-like figure won't come in the future. And this is assuming he fails in his attempt to destroy US democracy, which given the pathetic state of US domestic resistance is seeming less and less likely by the day.