They tried the "no end of the world" thing in DA2. From the time it dropped until shortly before DAI was released, I was one of the few people defending it on these boards. Most seemed to consider a failure because it was insufficiently epic.
Also, if you play the Templars route in DAI, you get to read Corypheus's journals. He's not a "drooling hellbeast." He's actually complicated, conflicted, interesting, capable of guilt and regret and spiritual pain.
The Archdemon fits that mould more, but read enough codex entries and you find out that Urthmiel was the most sympathetic of the old gods, a deity of festivals and art and beauty. They could have made us fight the more obviously evil Archdemon of Slaves or something, but they wanted a hint of tragedy even in that - though admittedly that takes a bit of research.
I'm looking forward to Solas and possibly Sten as villains. Both of those we know, they come pre-three-dimensionalized, so they make good villains. Both are capable of regret and remorse - and eliciting sympathy.
But I guess the real question we're asking here is if we want another Warden/Inquisitor, blessed and cursed with powers and a destiny to save the world? Or do we want another Hawke, and ordinary joe who just happens to be there and probably won't save anything other than their friends?
I'd be fine with the latter, but it would be hard to do that in a Tevinter setting. The Tevinters have three upper classes devoted to the human mage class alone, then human warriors and rogues below that. Qunari are likely attacked on sight, and the Tevinters basically see elves as magic-powering batteries that can be occasionally made to serve you dinner. Only dwarves can get friendly treatment in the Imperium as outsiders (provided they bring the lyrium).
Unless there's some remarkable explanation for why we're the hero here, it will be a very boring character creator. The good money is on getting some special power and a destiny to go with it.
The only other options would have to be someone from the outside - but why them and not someone else, which brings us back to special powers - or an anti-Inquisitor who's a criminal and outcast of society rather than the centre of a legitimate institution.