I can envision whitelist-only ISPs that block any traffic to unvetted domains and IPs. Hopefully we still have some time left before total dictatorship
As far as I know, what you describe exists today only in North Korea. Which is to say, this is not very likely. Thing is, a "great firewall" with some packet inspection thrown in to cut off the common VPN protocols deters 90% of the population, and that is generally "good enough" for authoritarians.