>Outright defeating a nearly-equal opponent is impossible in the nuclear age, so the only remaining problem is how to curb-stomp much weaker opponents as humanely as possible.
I think this is true as of today, but I don't know if this will remain true in the future because people will still seek out the ability to apply asymmetric means on another all else being equal, in ways that would probably be hard to combat.
However, such would depend on how one defines what such outright defeat would look like and I posit that the closer that one defines that with something that doesn't look like what usually is conjured up in minds when war is brought up, the more successful one is probably going to be (assuming one would want wage war to achieve some ends and is open to the option of winning such without leaving any trail of bodies in the wake).
Not a question for you, but for everyone who's interested, but what would outright defeat look like in the cyber-warfare today and tomorrow as the domain considered to be cyberspace continually expands to compose how we relate with one another and the world, where there will be economic incentive to place nanomachines in living organisms (things that "we" are doing now in research labs) that can communicate/execute complex logic manifested in the behavior of said organisms orders of magnitude faster than humans can even perceive (and have a really hard time even finding/observing now with the most expensive of equipment)?
Another good counter argument is that there were lots of wars between the US Civil War and World War II between first-class opponents of relatively similar capabilities, including both of those conflicts, World War I, the Franco-Prussian and Russo-Japanese wars. Since World War II, only arguably has the Korean War pitted two relatively equal foes against each other, and even then China had a huge advantage in manpower while the UN forces had a huge technological advantage.
If the NBA was dissolved and Golden State periodically faced college teams, 75 years from now they would probably still have a small-ball 3-point-shooting lineup. That's the state of military doctrine today. Outright defeating a nearly-equal opponent is impossible in the nuclear age, so the only remaining problem is how to curb-stomp much weaker opponents as humanely as possible.