If the virus mutates enough that it develops a completely different method of entering cells, it's essentially a different virus. This would change its rate of

If the virus mutates enough that it develops a completely different method of entering cells, it's essentially a different virus. This would change its rate of transmission, it's incubation period, its infectivity, even symptoms. It's no more likely that covid-19 mutates into the next pandemic virus than any of the other coronaviruses already in circulation do. Yes it's good to get people vaccinated quickly, there's certainly no good that will come from unnecessarily prolonging the current pandemic, but it will end.