Dashrashh, A DLC would be the best choice and the best money maker. I have several ideas from telling the story of the HoF and Leliana's travels after Vigil's Keep,time spent with Morrigan after they entered the mirror, while looking for the cure or time spent at Weisshaupt during the revolt. The DLC would be similar to Leliana's story or Witch Hunt-a short fun game.
For those that killed off their warden in DA:O they need not buy the DLC for those that kept their warden alive they have the return of their HoF. In the process BW makes money.
In my after blight/Vigil's Keep fan story my male warden travel with Leliana and after she return to the Chantry he return home to the Denerim Alienage and became a drunk. My female warden marries a human merchant in Denerim while my female mage warden joins Lanaya's clan as her second and dies 8 years after the blight from a fever. I'm not sure if I really want my warden to return but,would still buy and play the DLC since it would be part of the DA series.
You just excluded a very large proportion of the audience. A lot of people killed their warden, and now, 8 years later, an even larger proportion of the audience won't have even played Origins and will have gotten that ended as default.
In order to make to DLC, they must have reason to believe it would sell better than any other piece of DLC they could spend the development time on. So they have a choice -
1 - Make DLC with the current protagonist, which will be relevant to 100% of the audience that has bought the base game, where they know the player has all the relevant information to enjoy the content.
2 - Make DLC for half of the audience that bought a completely different game 8 years ago and made 1 specific choice. Anyone who made a different choice is excluded, anyone who didn't play that game is excluded, and even if they provide the option to change the default choice for those that didn't play the game, the content won't make any sense for them as it will be based around characters they don't know.
In order to make this DLC, 2 has to be more profitable than 1. I'm not seeing any way that can happen.