Regarding the "The story's not about Thedas because NPCs" argument:
They exist to tie you into the story.
What ties me to an interactive story is my character. Not some ever-so-mysteries supermages whose plans are way too complicated and important for us lowly players, not a gaggle of recurring NPCs, not cameos from tie-ins that I haven't even read. Do I care about favored NPCs as well? Of course I do. But that, too, happens primarily in the context of their bond to my character -- be it friendship or enmity. That is why I want fewer cases of ex-companions of ex-protagonists popping up: I'd actually like to be able to imagine that their friendships endured and that they remain together for once instead of scattering to all corners of the world without looking back as soon as the big bad is defeated.
I'm perfectly fine with an optional, well-written, meaningful death for my own characters if it fits them and the situation. As I said, I would never choose anything but the sacrifice in Origins, that was brilliantly and beautifully done. Likewise, I'm fine with an ex-protagonist no longer being involved in everything under the sun. But here is the thing: if the writers bring back 101 mysteries, friends, enemies, plotlines, places, and areas of expertise connected to an now ex-protagonist, then they only have themselves to blame when players wonder why the bleep said ex-protagonist is just about the only thing that isn't coming back.
I'm as sick and tired as anyone of the neverending clamor about the Warden, or the nonsense about how the optional Awakenings protagonist or an entirely new character could totally take the Warden's place and how we sacrifice-players thus totally need to get behind the demands for the Warden to come back as a protagonist. And that's if we're not ignored to begin with. So, yeah, I do get the desire to avoid such nonsense in further games if possible. But forcing the same death on each Inquisitor (or other future protagonists) no matter their past actions, goals, values or personalities is not the way to go about it.
Thedas is a big world. If Bioware actually lived up to their claim, they could easily move their focus to entirely new characters, faraway places, new themes. Or they could simply drop that inane, entirely arbitrary, not based on any in-world needs or logic "one game per protagonist, then it's off to the refuse pile with you" rule. Let us experience mysteries, plotlines and NPC arcs with the protagonist that was first connected to them. The experience would be all the stronger for it.