Everyone who I know who is antivax supports everything on that list. Boosting natural immunity, hygiene, better nutrition, any number of other health improvements.

I mean your premise seems to be that various diseases will reemerge and that will scare people into getting vaccines. But what if they end up healthier and so adapt in different ways? Better sanitation, immune boosters, improved forms of treatment, etc. What if the medical culture takes a totally different route because you allowed people not to get vaccinated?