...show that you got the vaccine and to force people to get the vaccine, would we still need the passport if everyone got the vaccine?
As an intellectual exercise, what would be the reason to still require showing it (for it to exist at all) if everyone took it or enough did for herd impunity to kick in?
They'll keep pushing for tiered passports depending on how many doses you've taken, with of course the populations they don't like being fed poison while the rest get a harmless saline solution.