> The 1918 flu pandemic ended without a vaccine. Covid will pass as well.
You're begging the question here. As best as we can tell, variants tend to come up when individual people mount a marginally effective immune response to the virus -- just enough to keep it in check but not enough to eradicate it. Effectively, they become a walking "gain of function" experiment.
Vaccines help at the outset by strengthening the immune response. They also help on a statistical basis by simply reducing the background rate of covid in a society. Given the development of new mutations with vaccine availability, we'd be likely to see as many or more mutations without widespread vaccination. If "covid will pass" without vaccination, then it will pass faster with, and the reverse implication is not necessarily true.
Remember, while the media often calls variants of concerns "vaccine escapes," the real effect is immune escape. If a new variant is more likely than average to cause a breakthrough case in a vaccinated person, it's also more likely than average to cause a reinfection in a recovered person.
If you want to be optimistic, then you can still hold out hope that new, more infectious variants may be less severe. The "human gain of function experiment" process for creating variants would select for both infectivity and non-severity. However, I do not have any data on the relative severity of B.1.1.529, and summer/early fall reporting on Delta suggested that it tended to cause somewhat more severe illness than Covid Classic.