DA4 will be an mmo. Mark my words. DA:I was the beta for it.
Bioware has already a MMO. Star Wars The Old Republic. Maintain two MMOs at the same time is hard. I mean, if they only make MMOs, maybe, but two MMOs, Mass Effect saga and some more new stuff they said they're working on? Don't think so. Also, note that Dragon Age lore is very close to player's choice. Even if there's a cannon... It's hard. Who is going to be the inquisitor? What about the divine? Sure, they can always try a MMO based in pre-origins events, like the first blight... Like Elder Scrolls did. And you see what response they got there. So no, I don't think so.
Ok. Now, to follow the thread here... What happens with the mage collage against mage circle? Or the future of templar order, the Wardens... There's a lot of things the epilogue left as a nice plots to future DLC. Maybe not in DA4, but a nice expansion pack like Awakening, with the Inquisition solving some "mundane" problems, maybe with more grey and hard choices.
And someone said it before... I really want an Inquisitor/Hawke/Warden team. At least for once, even if it's a short quest. I mean, my Warden was a tank warrior. Hawke was a rogue, and the Inquisitor, a mage. ¡It's damn perfect! XD. Maybe even some Citadel-type DLC with the three characters, a way to close the entire story and open a new plot.