All viruses mutate, but so far SARS-CoV-2 has been mutating relatively slowly. It has an error correction mechanism which blocks the majority of mutations. By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year.

The human species already has a significant level of herd immunity against four other endemic coronaviruses. The same thing will eventually happen with SARS-CoV-2 one way or another, but hopefully we will have an effective vaccine soon enough to accelerate that process while minimizing the death toll.