I really hope SE think about this and do it carefully.

Many of those areas are used by 'leveling up' content: city missions, AF coffers, Genkai drops, Kazham airship keys, quests, etc.

By making them into playgrounds for bored 90s+ they could easily make the original content those areas contain inaccessible or highly dependent on 'high level help' to complete for those still not in the 90s.