We already have 4 endemic coronaviruses that cause common colds, and we suspect that they started as deadly pandemics too, which were historically reported as the flu. Many specialists suspect that the OC43 coronavirus caused the 1889 "Russian flu".
Covid seems to follow the same path: a disease that is mostly harmless to the young but potentially deadly to older adults with no acquired immunity. It is likely that in a generation or two, everyone will be infected at a very young age, building immunity and occasionally get breakthrough colds. Breakthrough cases already look a lot like colds.
The second argument is that over a century ago, an epidemic might have possibly been caused by a coronavirus, and might have possibly become a common strain of the flu. This tenuous and unprovable line of reasoning is exactly what I see as wishful thinking.
https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/175...
Could do, yeah. I'm no evolutionary biologist, but I guess that for this to happen, it needs to mutate in various directions, and the strains to feel selection pressure to become non-lethal to humans. Which I guess means that a lot of people need to die of more lethal strains faster than they spread it, and that way the surviving strains will become the dominant strains while the people-killing strains wipe themselves out by killing their hosts quickly.
This does not feel like a great solution; using human deaths as a way to select for the less lethal variants. Feels like that involves a lot of humans dying, which people have a strong bias against.
Humanity suffered from smallpox for centuries before it was finally eradicated. It's not clear that it was becoming meaningfully less severe.
Dengue is endemic in tropical regions. A reinfection often leads to severe disease.
Yellow fever did not get better over time.
We vaccinated actual measles in children somewhere close to oblivion. Pockets of vaccine resistance still lead to localized outbreaks in the US. Measles is, according to most estimates, significantly more infectious that Delta, and yet we still managed to reach crowd immunity instead of throwing up our hands and relying on hopes and prayers.
Finally, HIV is perhaps our most recent experience with a viral epidemic. If we expect Covid to turn into a cold, maybe we should expect AIDS to turn into a cold first. It has a 40-year lead!