Your best case scenario is population collapse, but to do it without disease or conflict? Just everyone peacefully getting old and dying without having children?
Oftentimes, what's good for the empire isn't good for the citizens of the empire. So yeah, I'm happy to leave behind the wreckages of a dead empire if it means more for the people in that empire.
Unfortunately, I'm guessing that we'll get the war, or the pandemic, or both. That's how things have historically ended.
We have some additional complexities in that a lot of those growth limits are because of the interplay between economics and population. There's plenty more room for humans on earth; there's not more room within major metropolises without triggering our "It's too crowded; better not breed" instincts. But economic forces needed to sustain those high populations promote concentration and crowding.
It's quite normal to have a population that increases exponentially, hits resource limits, and then decreases rapidly. (This was like literally 1/3 of my calculus class - it's a pretty classic example for coupled partial differential equations.) Eventually the population declines enough that the resource limits no longer apply, and people start having babies again. Population isn't a monolithic concept: there will always be some women who have children regardless of their incentives.
I'll just be happy if we can get there without war, famine, pestilence, and death, which are the normal results when a society hits resource limits.