>> Lower mortality but easier transmission <<
Definitely. That’s the evolutionary mechanism at work. If the virus “wants” to survive, it’s got to stop killing almost everybody it infects. It needs to have victims who are walking around and infecting others, not corpses buried in the ground.
Then as time goes by, the virus will tend to get even weaker, until ordinary public health and sanitary measures can keep it under control, at least in developed economies like those of the USA and Europe.
Bottom line:
Such a virus may never disappear entirely, and there may be occasional bad outbreaks, but it is very unlikely to become the “monster” pandemic of sci-fi movies.
Smallpox never became non pandemic on its own.
We have no idea if this will either.
It may mutate and become totally airborne before it lowers its mortality rate.
Still, even a 30% mortality rate and airborne would be a herd thinner fur sure.