I've been meaning to ask, since I don't know anything about game dev:
Is there some technical challenge about having Inky return as protagonist? Or is it purely a question of how they envision the game and the plot and how the Inquisitor fits with that?
I'm not a game dev, so at best I can offer the best guess, based on my observations and some stuff devs said in interviews or panels.
Anyway, I suppose the biggest challenge would likely be one of balancing between their own vision AND attracting new players to the franchise. For those new who come to the franchise, playing an already well-established character (especially with so many variants between them - who they romanced, are they more diplomatic or aggressive) may be somewhat off-putting, though the success of ME series suggests that it's not something that's undoable.
In fact, the lead writer now is someone who worked years on ME franchise - which itself suggests that they may indeed go the route of either keeping Inky as protagonist or secondary protag, since people responsible for the story know how to write it for recurring, customizable characters.
The difference between DA and ME is that we seem to have (on surface, at least) more options for creating our characters: different races, different backgrounds, somewhat different reactions to races and backgrounds, etc. - I suspect that itself may decide many things about the scope of the game, seeing that voiceover and cutscenes seem to be really expensive and time-consuming to create (unless they have some sort of new technology that will help them quickly re-adjust animations to different body models or something). Really, when it comes to this, I can only guess.
The biggest problem I see now for Inky to be the main character is... well... romanceability. Let's face it - as optional as they are, romances are a staple of BW games. And in Inquisition/Treaspasser Quizzies can even marry some of their companions or advisers. Not really sure that can be reconciled, especially with new, interesting characters who will likely be romanceable too.
That is likely the biggest challenge of bringing Inky as main protag, because it would likely require to bring their LIs at some measure - and creating a lot of content that will be locked out and never accessed, especially by newcomers, is likely the biggest issue. With dual protagonist that aspect of Inky's life can likely be pushed farther into the background - some codexes, some comments, maybe a short cutscene or two where they interact in a small measure...
At least, that's the way I see it.