The odds that it mutates into one that is both more dangerous (that is, higher fatality rate) and more communicable are very low.

Corona viruses (and there have been many) usually mutate to become less dangerous - because dead hosts don’t spread the virus.

From a virus’s perspective (and yes, I know, viruses don’t have perspectives) the ideal strategy is to be very highly communicable and not dangerous at all. In fact, there could well be many such viruses at loose - if everyone’s asymptomatic, no one knows they have it.