The potential vaccine evading new variant mantra has become the "chicken little" of COVID. Other than the constant new strains of influenza which I'm not sure is really the same thing, what virus has mutated to evade a vaccine since vaccines were discovered? I'm genuinely asking. Without clear examples, that narrative becomes just another scare tactic that will end up doing the opposite of increasing vaccine acceptance.
It is basically saying "get vaccinated but if enough people in the world don't get vaccinated quickly enough then the vaccine probably won't work long term anyway." Not really a compelling sales pitch for the hesitant/resistant.
A lot of things could happen. A bat could poop onto somebody's head an start the spread of a whole new virus for which there isn't a vaccine and that virus could be more deadly than COVID-19.