There will be a point where COVID will just be a nasty flu that the vulnerable will receive boosters for.
It just has to.
This is what is known technically as wishful thinking.
Covid isn't flu and has no reason to mutate into a form as mild as flu for the foreseeable future. If we're lucky it won't mutate into something much worse, but we just don't know.
Comparisons with Spanish Flu are false - in a way the initial covid epidemic is over, because the virus spreading today isn't the one that did so in the first wave. And if there's a 3rd wave, it will likely be a different variant again. Covid if you like is a succession of short epidemics.
Spanish Flu on the other hand, if we're talking about the killer epidemic, was a single unusual variant of influenza - after people had gained some immunity to it, it mutated into something milder and more normal for flu.
Every covid mutation so far has increased both infectiousness and disease severity. The baseline with covid is 1000x more serious than influenza. It's a brand new disease and if it becomes endemic then we could see new epidemics sweeping the country every year, as we do with flu, but 1000x worse.
Personally I don't like the look of this future - that's why zero covid is the only sensible strategy. The long term costs of dealing with regular outbreaks are far far higher than the costs of dealing with the problem now. I don't want annual lockdowns.