Though I'm aware of the improbabilities of something like the OP suggested could happen at this point, it would have been a really good idea if it was created from day 1 in the development process of DA3. One of the biggest holes (and certainly not the only one), I found trying to enjoy playing inquisition is that the name Hawke was written all over the place in the main plot. I felt, way too many times, as if this "blank slate" inquisitor who was turned from a no one to a revered saviour of the world in almost an hour, was cheap writing and was not believable. The war between mages and templars was, for me, a conflict that was a mission for Hawke to solve. Coryphaeus was also Hawke's antagonist and it seems the devs/writers couldn't find a way to make it right with the antagonist when they decided to go with this inquisitor as the pc so they literally turned him into a sort of absent, almost funny cartoonish coyote who permanently fails at every attempt of getting his blighty hands on this roadrunner/inqui to a point where he just stop showing until the very end.
As for the implementation of the four different races in DAI, I just would say that I hope that if they decide to keep wasting budget/time resources implementing them in the next game, they find a way to balance that feature with the quality of the story. This in a sense that we have a next game where the execution of the story won't suffer because they had to spend so much time/money making every single bit of the game available for 8 different protagonist (four females/four male).
If i understand correctly, Bioware had an extra year granted by EA to implement these races into a game that, I imagine, was more or less developed. How much great content was probably cut because they didn't have the time/budget to make this already existing parts of the story available to these new protagonist?