There's a common fairy tale that COVID will evolve to become more docile, because that's what viruses do, or something. You know, like smallpox.
It seems much more likely to me that it will continue to become more contagious, and the fatality rate could go either direction. (COVID kills a small enough percentage late enough in the course that there's little to no selective pressure to reduce mortality.) But it will become less of a problem as more and more people are exposed to some variant or vaccinated, so the evolved variants have no "naive" population to devastate.
Vietnam's latest is apparently a branch from the India strain, with an additional mutation also found in the UK variant. That likely makes it more deadly than the original and at least twice as contagious. Our vaccines should give reasonable protection, but probably not enough for herd immunity. Fortunately, the vaccines still seem to offer almost complete protection from severe COVID or death even with variants seen so far.
Naive older people getting COVID have it worse, 50 years from now most old people will have had it as kids or been vaccinated.
I think when you have neutralizing antibodies, it tends to shut the infection down fairly quickly, and you tend not toe reach the cytokine storm stage. (As I understand it that usually happens 2 weeks or more post infection.) But I'm not up to speed there.
The corollary of this argument is that the effect of COVID (including its variants) on humanity may significantly diminish over time to possibly that of the common cold, where the majority of people are exposed to it very early and so it never affects them much, even with multiple reinfections.
My understanding is that alot of the worst outcomes are due to autoimmune responses, cytokine storms or the like. If that's true, then arguably young humans with trainable immune systems will be less susceptible as they grow older, because their immune systems are going to encounter COVID regularly, and learn not to over-react.