IMO, Tevinter seems like the destination for the next game. Lore-wise, it's the most "magical" setting in modern Thedas, and gives gamers to explore potential answers to the really big questions of the DA mythos - The nature of the Fade, Veil, Blights, Old Gods, etc.
Politically, you have the internal chaos in the wake of Venatori meddling in the south and the ongoing conflict with the Qunari - which means plenty of room for Tevinter/Qunari-related character cameos. Fenris leading slave uprisings? Dorian trying to restore a moderate element to the magocracy? Sten Arishok-ing? All sorts of fun potential.
I'm hoping for Origin stories and a new protagonist. That said, I'm pretty sure we're unlikely to see Origin stories ever again, because they're extremely hard for developers - time wise, they represent a lot of investment by devs in non-skippable "main quest" type material. When devs creature mutually-exclusive quest paths, these tend to be limited to binary options - In Hushed Whispers vs Champions of the Just, for example. Origins had 6 (2 elf, 2 dwarf, human, mage) mutually exclusive introductions. Developer-wise it tends to make more sense for them to make fewer intro options, and use the extra time on a main quest everyone gets to enjoy. That said, I've got a pretty good work-around in mind if they decide to use Tevinter as the setting. (You're part of a House, but whether you're a noble, servant, slave, visiting emissary, etc... to start with is up to you. Would let them use the same area for every introduction but have whatever you're up to before the initial DRAMATIC MOMENT vary.)