It should be noted that for Sars-Cov-2 specifically (i.e. given a virus that has the properties of Sars-Cov-2 already) lethality will likely be a neutral factor

It should be noted that for Sars-Cov-2 specifically (i.e. given a virus that has the properties of Sars-Cov-2 already) lethality will likely be a neutral factor for the evolution going forward. The reason being that viral titres peak around day 2 in a window of 1-5 days, whereas it takes at lot longer to die from Covid. In other words there is same sort of cap where lethality prevents transmission, but Sars-Cov-2 is nowhere near it.