"Repeated exposures might train the upper respiratory tract over periods of months to spot and neutralize it within seconds."

This is the idea behind a self-spreading viral "coronavirus vaccine," and may be what SARS-CoV-2 was actually designed to be (as JJ Couey puts it, it's an incredibly stupid idea but it writes grant applications). As for whether the mRNA / vector Covid vaccines create the same "pass on immunization," I agree there should be way more curiosity out in the research.

But the implications would probably be negative. Normal T Cell immunity does not obsess over spike - there are much more stable coronavirus proteins to go after. So the individual immune system doesn't vote in favor of the plan. And the "species immune system" seems to vote against sustained pressure on spike protein as well - rather, antibodies drift, allowing the virus to survive and proliferate without having to innovate in spike all the time. I'm not very convinced that the Covid vaccines actually drove the increased rate in spike evolution that began just about a year ago, nor that they are driving it now. After all, cases seem to be increasing all around now that everyone has left the "infection efficacy" window. Why would the virus bother trying to escape antibodies that aren't stopping infection? But, of course, the boosters put such an event on the table. The point is that even if the outcome (increasing population-wide "sterilizing" immunity + driving spike escape) is unlikely, it's undesirable.