I think you underestimate the probability of a sudden die off of a large share of the human population : they have happened regularly in the past, and our bio-medical technology might not be able to prevent a new, fast spreading disease.

See what is happening with AIDS in Africa ; the same could actually happen, as it did with the Plague before the Renaissance.

BTW, the Renaissance was literally a rebirth of population at the end of the middle ages ; it had been almost divided by two after the Plague and the Hundred Years wars. The subsequent social and cultural transformations, as humans became rarer, were major factors in starting up the Renaissance.

Un roi sans divertissement est un homme plein de misères