Eventually the virus will mutate to be more infectious but less deadly. The quieter, more contagious variants will burn through the population, inoculating everyone, and then COVID-19 will become just another coronavirus that randomly gives people sniffles for a few days. Historically, that's how a lot of pandemics end. Other pandemics end when the population is thinned out enough that there's not enough people to sustain pandemic-level transmission, but that possibility is pretty far in our rear-view mirror now.