Nothing is going to happen about follower missions. They've stripped those to the most barebones they can, and I supposed they're going to scrap those at one expansion or another.
Same for island expeditions. They were supposed to be the greatest thing since AlphaGo or something (haven't watched the AI Starcraft yesterday...), and then they fizzled into nothingness. They have a pipeline of island settings and mob placement to finish emptying so I assume we'll see two new islands on 8.2 with some additional mobs, and that will be it.