The potential "collapse" of the US Military (and what does that mean, specifically?) hinders on the assumption that the US will be engaged in foreign conflicts across the globe.

I think we'll turn isolationist well before that becomes a reality. Foreign policy wonks can talk up and down about the necessity of American troops to protect human interests in Bangladesh, and to prevent destabilization of neighbors, potential conflict involving nuclear states... but I have trouble seeing the Senate voting to deploy troops when their constituency thinks, "who gives a shit about Bangladesh?"