I think all those famdoms, main wikipedia etc should be backed up in multiple archives and should be provided to as many libraries for offline read.

many "fandom" wikis have alternatives. If you can spare the time, scroll a little bit further down in your search results. They exist! And for the ones that do not have a "fandom" wiki, there are alternative readers.

Fandom is truly cancerous. I have not checked whether they are affiliated with Wikimedia, but I would not be surprised if that was the case!

Good news, that's all already happened!