I personally don't want that to be China. Not because I think they'd do a bunch of crazy things but because I think they'd slowly and methodically subvert other countries just like they're doing in the South China Sea.
While I agree 1000% we need to minimize the USA military, we also need a plan for other (UN) countries to contribute to a shared force or something similar that can police in place of the USA military. Even in turn policing the USA in cases of military overstepping.
EDIT: What I'm saying is this article points to a problem, but it's complex. I imagine with UN oversight a military force might actually be less of a polluter and we might slow down arms races as well.