I'm afraid this is a naive view on the virulence / transmissibility tradeoff in pathogens. A reduction in virulence is only expected to happen in strictly vertically transmitted pathogens (e.g. mother to child), where the pathogen and host fitness are strictly linked.
(1/5) https://twitter.com/MLevitt_NP2013/status/1276793878440562688

Under horizontal disease transmission, as is the case for epidemic pathogens such as #SARSCoV2, essentially any evolutionary trajectory is possible. Evolution of virulence depends on host population structure, and within-host viral replication, among other things.
(2/5)

#SARSCoV2 is not lethal enough to be under strong selection for reduced virulence. The small proportion of hosts killed won't significantly affect its transmission. Besides, transmission of #COVID19 tends to happen early in the infection, sometimes before symptoms.
(3/5)

The burden of #COVID19 will decrease over time as immunisation in the population builds up through infection/vaccination. Though, there is no particular reason to believe #SARSCoV2 will become intrinsically more/less virulent/transmissible.
(4/5)

There is no convincing evidence suggesting #SARSCoV2 has become more/less transmissible/virulent since it jumped into humans in late 2019. The mutations acquired by the global viral population until now are apparently all 'segregating neutrally'.
(5/5)
https://doi.org/10.1101/2020.05.21.108506