Here we are at 100 years since WWI. The thought at that time was the war would be over in a matter of days. Rail cars full of soldiers heading off to fight had hand painted signs saying they were on the way to the other side's capitol. It didn't work out that way and the war dragged on and on leaving millions and millions dead.
I am not sure it would be really different now. The assumption stated here is that it would be a nuclear war. Anybody who actually has those weapons knows better than to use them as it would lead to an "On the Beach" scenario. We are more likely to end up in a war with an adversary that uses "assymetric" warfare to achieve their objective - much like the mess we waded into in Afghanistan and Iraq. Those are still dragging on, but so far no draft.
If things get bad enough they will take anyone...
Erin