>> it’s not clear that the Omicron flash flood will substantially strengthen our wall of immunity much

There seems to be a good amount of T-Cell response to Omicron in individuals either vaccinated or convalescent from previous infection (preprint here), which makes expecting the response to future variants at least not unreasonable. That's CD-8/CD-4 T-cell response, not antibodies, so not absolute immunity, but hospitalization rates should reflect this.

None of this gives us a free pass around the "vulnerable, elderly, or immunocompromised" any more than it would if you had, say, influenza.