If that happens before a mutation spreads which renders the vaccines useless. And, seeing the pace at which vaccination is progressing in poorer countries, I'm not really optimistic about that. On the other hand, there is still hope that the vaccine will at least keep you from getting seriously sick if you get infected with a vaccine-resistant strain...
There is no reason to believe a mutation is going to render major vaccines useless. The real-life results of the mRNA vaccines against the major variants are very encouraging (see e.g. https://www.nbcnews.com/news/us-news/pfizer-says-trials-sugg...). Many of the scary lab results were only testing the virus against antibodies, not the full power of a vaccinated person's immune system.
I'm not saying the vaccines aren't effective against the current variants of concern, but the situation with part of the population vaccinated and mass transmission in the unvaccinated part of the population may favor the emergence of a new vaccine-resistant strain.
If that happens before a mutation spreads which renders the vaccines useless. And, seeing the pace at which vaccination is progressing in poorer countries, I'm not really optimistic about that. On the other hand, there is still hope that the vaccine will at least keep you from getting seriously sick if you get infected with a vaccine-resistant strain...