The future of NATO is secure. It just won't include the US. Whether that exclusion is done implicitly or explicitly remains to be seen. The US has put itself in the position where it has no allies and no peaceful trading partners. That's not going to work out well for them, regardless of how much military might they believe they have.
NATO is an alliance of 32 democracies and from time to time some of those will vote in unfortunate leaders. I guess the remainder will have to carry on. I doubt the US will remain this way after the next election.
