Rapid and unpredictable mutation of RNA viruses means it will be difficult to keep vaccine design and production on pace with viral evolution. This raises questions about a vaccine's ability to offer full, long term protection against SARS-CoV-2 variants, even with booster shots.
Cure-Hub's data shows less antibody diversity in vaccinated individuals than naturally infected individuals. Fewer unique antibodies provide the virus with an avenue for immune escape through S protein mutations.
When you do have natural immunity you will have more comprehensive antibody protection. After almost everyone has some natural immunity, it will be more difficult to transmit the virus.
TL;DR:
Booster reliant persons now exist.
And they hate us.