Luckily here in America we have hundreds of millions of men and women to give up to the altar of democracy, right? We’re not France in 1915 or 1939. Not only that, but maybe you want to consider more modern war’s attrition rates.
Big assumption. Other options are also North Korea sending troops. Or Iran. Or while the US engages there, China uses the opportunity to take Taiwan. Geopolitics is complicated. No one wants a nuclear war, but at some point there is no more rationality, when a side feels pushed over the limit.
That's never been doctorine for the simple reason US hasn't had (near) peer rivals until PRC in last 30 years. Peak hyperpower US 90s doctorine was calibrated for 2 "major" wars, when major is with adversaries who were frankly all medium powers (IRAQ tier). Then in 00s-10s it shifted to 1 "major" war, 1 holding war, i.e. actively fight 1 major war, fix another major war in place so resources can shift to second war after active war. Now half the think tank writing is questioning if US can win in PRC backyard, where PRC is characterized either as near peer, pacing power, or peer. US doctorine right now is maybe can deter PRC until post 2030s "decade of concern" but right now US IndoPac posture in PRC backyard a tossup.
There’s a few anomalies where old dudes are sticking around voluntarily.
Also worth noting that a lot of the videos posted claiming to be “people being drafted” are actually videos of the police just arresting criminals…