There's no guarantee that it will work that way: smallpox didn't get less deadly. Only vaccination wiped it out.
If the patient is contagious before developing symptoms, the virus can spread very effectively even if many patients die.
If the patient is contagious before developing symptoms, the virus can spread very effectively even if many patients die.
For better or worse all that means is that viruses may evolve to delay their symptoms rather than overall peak severity if that's possible. It means still just as delay but with a good enough delay to spread.
I don't really see the selective pressure however for this virus to become more benign. It seems to have enough people to infect without it given how contagious it is. It doesn't really have to become more benign to allow even more spread.
Age and Date Data: [https://www.cdc.gov/nchs/nvss/vsrr/covid_weekly/index.htm#Se...]