Board Thread:New Features/@comment-5275700-20161013173857/@comment-24258073-20161107024322

Wikia Staff did say when they introduced the new discussions that they intended to keep the old forums available but eventually replace the new forums with discussions. I have no idea why it's no longer possible to change on the wiki features, but I assume they'll make it available for users to choose between old forums and discussions once they've perfected the new discussions feature and replaced the new forums entirely.