That's true, natural infection could also serve as a booster for those who are vaccinated, at least in theory. Controversially, this way might even be more cost-effective considering that (1) vaccines still protect against severe Covid-19 and (2) vaccine supplies are unequally distributed globally. Plus, I'm not sure if vaccine hesitancy will increase or remain unchanged when boosters are implemented.

Anyway, I also agree that there will always be unanticipated problems; who knows if climate change will give rise to new forms of diseases. There's also evidence suggesting that climate change that shifted bat's habitats might have triggered the SARS-CoV-2 spillover.