Kind of, maybe. Domesticated animals are still in the wild in many places, so if there was any desire to "start from scratch", so to say, it can be done.

This reminded me of some places with high boar populations, you can hunt them anytime since they're overrunning the ecosystem basically.

Yet people don't like their meat because it's "too gamey", whatever that means.

There's also the oily fish species that everyone seems to hate but they actually taste good and are nutritious.

Point is, the reason for the lack genetic diversity in food supply is people - they simply don't want diversity. We've found the best tasting or more versatile food and everyone's going with that.

I have no doubt that diets will adapt if some crops or animals completely disappear somehow.

Diversity of overall flora and Fauna is indeed screwed. So many species are near extinct already and few care.