re: How well would the U.S.population actually fare in an all-out war today?

It's interesting to think about Vietnam and what exactly "winning" would look like. The goals were to industrialize Vietnam, maintain Western(Fr. Indochina) influence/hegemony in the region, stop an insurection/prevent a true revolution & total loss of government(arguably this included inducing a revolution/reuinification of N & S Vietnam), and stopping the spread of communism. The goal wasn't to conquer a nation and occupy it militarily/by force, something that would require extensive resources indefinitely

Seems to me that all was accomplished as the Vietcong mostly transitioned from being independent farmers to participants in a developing industrial society, Western influence being retained throughout SE Asia, Communism was mostly halted, a government being mantained with the country unified, and Vietnam itself starting peaceful diplomatic relations with the UN/US almost immediately after the US exodus(textiling and letting big oil drill offshores).

Assuming your ultimate goals were accomplished, what's the differcence between winning and losing. "The easiest way to get rid of your enemy is to make him your friend". Maybe, just maybe, sometimes the only way to actually win a war, as in accomplish your goals, is to lose it on purpose