It's not going to happen. You couldn't get enough able-bodied people to show up or communities to enforce it. The ideals that made this possible for Vietnam will die with the boomers.
If we go to war with China, and it's not just some minor skirmish, I expect there to be a draft.
You might see people drafted into factories, given how much stuff is made in China and the impact on global trade, though.
The desert stuff was not so bad by comparison. These were asymmetrical conflicts. The emerging threats are near-peer forces. Even fewer will want to sign up for that!
>I expect there to be a draft.
And if there is a draft there will be mass noncompliance. It won't work. If they're smart they won't try it because that would look weak.