How can we make sure the web survives societal collapse?

Create an archive of it, save the data based on dates. Scrub the web and scrape the sites. Some day in the future there will be storage large enough to hold the whole Internet Archive for viewing.

Sort of what: http://archive.org does.

Video games that use servers will have to have open source versions written to support the old games. So that anyone can run a server for them.

For example Avengers Alliance on Facebook is dead. Everyone who paid into it for extra gold, hero skins, weapons, etc have nothing now. Some people are trying to rewrite the game for a local play.