Hmm, good question. They already did the D&D ripoff a classical fantasy game and jumped on the space opera bandwagon one of the sci-fi genre. What they need to do is something inspired by the eastern cultures. Then they'll have gone full circle around their old games. Aside from MDK 2 - I don't see them make anything similar any time soon.
Yeah, they still have Dragon Age, which seems to be intended as a longer running franchise and TOR, which I have no idea ho it's doing. And aside from those two they hold the license to Mass Effect - I doubt they'll let it go. Perhaps we'll have to wait but I can imagine they want to do more with the ME universe.
But if they go for a new IP (I don't see why not) I'm not sure what they'll have - they have medieval and future ages covered. I doubt they'll make a DA rival so it'd be either future, alternative present or some hybrid. If I had to choose one, I'd go with alternative present (or close) with magic and stuff.