How quickly can we sequence a mutated covid and develop a new vaccine? How do mutations in covid correlate with ease of developing an updated vaccine, i.e. is the previous vaccine a good starting point? Will it take a year to respond to each annual mutation, rendering vaccines almost useless? Presumably, there exist people with experience developing annual vaccines for influenza? These are all rhetorical questions that I'm shouting into the e-wind, no worries.
I think it depends a lot on immunology, which we don't have a good handle on yet (and won't for some time). The reason you can keep getting the same cold over and over is that the disease is mild and doesn't evoke a strong antibody response, so many people lose their immunity in a few years. Colds, as we've all learned, are coronaviruses. So that's ok the bad ledger. But I've read that SARS left people with strong immunity for 10 years or more, so that's in the good ledger. Hopefully because of the severity of SARS2, we'll also see strong antibodies in lots of people. That will lower the vaccine barrier a lot.