I just replayed through both games and most of their DLC. Then I read up on the third game, which will no doubt be good from what I have read. I did find a few things interesting though, BioWare says the Warden's story is done, with no real mention of Hawke. It was hinted that they both went off somewhere together to probably fight some new evil.
Firstly, I find it kind of sad that they won't use the Warden, but when they decided to make Hawke fully voiced, they pretty much shut that door. As for Hawke, well, I find him/her to be pretty damn awesome. I don't know if the cannon Hawke is a Mage, but that would make the most sense. At least in my mind, with the whole uprising and such.
By the way, this whole protagonist going off to fight hidden evil, remind you of a certain Republic? An Old Republic? ;)
Now, this is what I think will happen in Inquisition: You are the Inquisitor, you get the templars and mages to join forces to close the veil thus causing a peace After that, the Inquisitor goes off to join the Warden and Hawke. Morrigan plays the role Flemeth did in the previous 2 games, that being the Witch that helps our hero escape the inescapable in the first act.
As for returning companions besides Varic? Who knows. I'll tell you who won't be there though, Wynne, cause she's dead. Other than that, I expect Lelianna, Isabella, Sten(now Arishok), Alistair, Sebastian, and of course, Sandal to show up(because in act 3 of DA:2, Bohdan said they were going to the Empresses court in Orlais, which is where this game is largely taking place), not necessarily as companions mind you. Characters I do not care to see: Avaline; straight up boring, Merril; a very stupid person with flawed views, Ohgren; not funny, not useful.
Companions I would like to see: Anders; fully expect he'll be one of the mage leaders, Fenris; will just be some slaver resistance cameo in tevinter, Shale; because she's awesome, Carver/Bethany; because of the Hawke connection.
Here's what I think will happen in Dragon Age 3: You start off as nobody, but it is revealed about half way through the game that you are The Warden and Morrigan's child. As for the antagonist, it will most likely Flemeth. There is just too much we don't know about her. But what of our other 3 heroes? They are now Flemeth's Thralls, and you have to go through each of them in turn to get to her. That would go like this: Inquisitor-Hawke-Warden. With a touching scene of Father/child reunion if your Warden was male. Granted this whole situation only works if BioWare decides to ignore previous save files and go cannon.
Anyway, that's what I think will happen. But what do you think?