Its something i have been thinking about for a while now when it hit me like a ton of bricks AKAVIR! we've explored so much of tamriel in the previous games i think its time to venture into the other continents of nirn, it will be hard to leave the races we've all come to love behind i know but the possibilities are endless choosing to pick the snow demons of kamal, tsaesci, monkey people of tang mo, and the tiger dragons of kapotun. I know a lot of people would be opposed to the idea because of how loved tamriel is but if anybody could make it work its bethesda.
I think the next game will be in either Eleswer or Black Marsh. The only reason I think this is that they haven't made a game in one of the beast race land's.
Personally, I doubt we'll see akavir until tamriel has been well and truly exhausted. I'd like to see summerset isle next, lore-wise it'd give them good scope to flesh the magic system back out again, not to mention revisit morrowinds visual style.