Most of the deep cosmological knowledge we have is not widely known. An interview I saw somewhere said most people aren't even aware of the planet's own name.

After we spent an entire expansion on another world, I seriously doubt we're going to yet another so soon. The recent interview of Yoshi-P up on GameSpot said to brush up on Heavensward for 6.0, so Meracydia or (less likely) Sharlayan are the main contenders without further input.

(Side note: the Yo-Kai Watch event is getting another run the week after the patch drops, now updated with new class weapons and a Jibanyan floating chair mount if you collect them all.)