How should we change our investing strategy for the coming population collapse?

I've been following the Bogleheads way of buying the Index so most of my investments are in various index funds. However, we're approaching uncharted territory in a few places:

1. fertility is collapsing and the population is aging so soon most citizens will be beneficiaries of the state and the working age population can expect to be taxed more

2. The national debt associated with said collapse shows no sign of decreasing.

We have 250 years of data showing that, in the long term, betting on the American economy is a good idea. However, said previous data didn't have the same variables we have now as population collapse is unprecedented in human history outside of natural disasters, plague, or war. Should we change the way we invest?