I wonder with IPV6 could you not come up with a IP hopping protocol so that you can't actually block specific hosts without way too much effort? Maybe it would not work for the general internet, but maybe for some alternative just for this kind of situation?
With this sort of thing, you tend to block networks, not individual IPs. Regardless of how many IPv6 addresses you can use, they're going to be groupable, most likely.
Agreed, collateral blocks are not necessarily your worries in such scenarios. You could block all of the (e.g.) AWS datacenters for all that matters, if your endgame is preventing access to social media services.
