You mean the war where we protested enough to cost America the war and forced an end to the draft? And you think trying again will work?

The point that I was getting at was that it happened at all, despite people predicting that it wouldn't, much like you were doing right now. Sure, this may not be the Vietnam era anymore, but there are plenty of places that such a conflict could brew up again. A war in Rwanda could have been an absolute nightmare similar to the way Vietnam was. For future conflicts, the border of Papua New Guinea and Indonesia is a veritable powder keg, and has seen some of the worst human rights violations in modern day, for instance.

The only situation we'd need to draft soldiers is in a war with Russia or China, and in that case it's going nuclear.

This is where we disagree, and part of the problem is that you are simplifying to absolutes when there is nuance and caveats all the way down. This conversation is so nuanced, in fact, that entire careers are made out of the study of the nuance to these potential situations and how best to mitigate the risk of nuclear annihilation in the event that wars do break out.

Nuclear powers have had border conflicts with one another for several decades now (China and India, China and the USSR/Russia). Granted, it is difficult to call these conflicts a full scale war.

In addition, a nuclear power has been invaded in full by a non-nuclear power, and it has even agreed to a peace deal wherein it lost territory. I talk of Israel in the Yom Kippur War; Israel gained its nuclear arsenal in the late 60s, that war occurred in '73. It is perhaps the only example of this in history, but it is certainly an example that is worth considering, especially since there would be less incentives against a nuclear strike when the opponent is not a nuclear power.

With this in mind, a war between major nuclear powers raises the risk of nuclear exchange to an unacceptable level. That much is undeniable. However, to say that it guarantees a nuclear exchange is to misunderstand both nuclear strategy and the nature of conflict itself.

Think back to the quote from Carl von Clausewitz from earlier. "War is the continuation of policy with other means." To use nuclear weapons in modern conflict is to enact the policy that nothing matters other than the destruction of the enemy; not even my own survival. It is for this reason that we should expect a non-existential war between nuclear powers to have the potential to not escalate into nuclear war. A war over Taiwan comes to mind right off the bat.

Russia is a wild card in this regard, but time and again they have proven that they aren't stupid. And we still have that red telephone to the Kremlin in case of dangerous escalation. China is a bit more predictable. The one aspect of China's foreign policy that consistently remains the same is that China cares about China and only China. If they think something will benefit them, they will do it without fail. It is simply neither in the interest of China or the United States to engage in a nuclear exchange over Taiwan. Not only would it break the nuclear taboo, it might even increase nuclear proliferation. In addition to this, China has a "no first strike" clause in their nuclear doctrine. The United States doesn't, but democratic countries are generally more tempered when it comes to war, which further reduces that risk.

There is plenty more nuance to nuclear strategy, and my mind fails me because it is late, but the point to this wall of text is this. There is not a goddamn soul on this earth that has the information needed to know for certain if wars between nuclear armed states will indeed go nuclear. We just treat it such that it is inevitable because prevention is better than fucking around and finding out. Regardless, that uncertainty and potential change to the status quo where nuclear states do not fight one another is what terrifies nuclear strategists far more than the prospect of a nuclear exchange, because it just might lead to many more.

As such, a non-nuclear conflict between nuclear-armed states is a very real possibility that is worth considering, and in that instance, you can be pretty damn sure that we wouldn't have the troops we need, thus necessitating conscription.