Yeah a cameo was what I had in mind, but I simply do not trust BioWare to be able to pull it off effectively. I don't think Hawke was done all that well, and this character is far simpler to implement than the Warden.
My thing is, it's not so much that the Warden didn't speak, or that the new voices wouldn't sound like the generic battle calls (I couldn't care less about the difference), but rather the portrayal of the character as an NPC. I feel like this is something that they'll never really nail, and should just let go of.
As for the Dalish accent, needless to say the American accent for the Dalish is dead. It would either be the extra accent or just share the British default with human, though if it goes like Inquisition, you'd simply choose on a slider.
It's just a question of implementation, and that's simple. If they don't get it right, honestly, it's because their priorities were in the wrong place. All that would say is that they don't value our characterization of our PCs enough, maybe that they don't like the idea of variable characters really having any kind of central place. All I could say to that is they have the wrong idea, and they're making it appear a lot more difficult to accomplish than it actually is. The toughest thing isn't the Warden's personality or motivation or voice or whatever; it's just trying to include the other related characters. That expense could be mitigated by including those characters regardless of whether they were romanced or killed off in somebody's pt or what have you. If a character should logically appear, they do so, if not then not. Then it's just a matter of alternate dialogue around simple binary stances you could determine with dialogue or a short checklist. It's not so hard. It's really about how reluctant they are to centrally feature characters they don't have total conceptual control over.
Hawke's bloodmage stance and whatever are only an issue to people that care about that because BioWare chose not to give us an option, not because it's so difficult to do. And they probably made that choice because of Hawke's split vocal personality, because they thought, 'Uh, no, that one alternate line of dialogue needs six variables. Word budget, no good. ' The Warden, Inquisitor, and any future pc don't have that problem. Instead of six, there's two. Instead of 12 given a choice for that line, there's four. It's more than doable.
edit: Obviously if a character died, they just wouldn't show unless their death was easy to explain away. The Warden themself is an either/or with DA:A's. Yes, they'd need another accent, not necessarily another voice actor.