Hmm... Sounds cool, but I can't help but think about all the complications of trying to make it work...
One: the combat in DA:O and DA2 is different from that in DA:I from what we've seen.
Two: Several specializations have been removed/changed (i.e.: Arcane Warrior, Champion, Shapeshifter, Spirit Warrior, Legionnaire Scout, Ranger, Battlemage, Keeper) so Wardens with those specs will have to be altered as well.
Three: Weapons. Since a warrior in DA:O can use any weapon except a staff and the DA2 equivalent can only be a S&S or two-hander warrior, it will be very complicated to figure out how to make builds like DW and archer warriors work in DA:I. Not to mention that in DA2, rogues we limited to daggers or bows.
Four: Fighting styles will make things complicated. You can play as a DW warrior, S&S warrior, archer warrior, or two-hander warrior in DA2 and DW rogues can use any one-handed weapon they have the strength/dexterity to use in DA:O. Obviously, this won't return in DA:I.
Five: Tactics. As we all know, you could set your tactics to have your Warden/Hawke and companions fight in a way that best suited your play style. And since the vast majority of abilities/spells we had in DA:O and Awakening were taken away in DA2, it is likely that not many will return, if any. This will also cause complications with whatever fighting they may be involved in. Same goes for Hawke. Like with DA:O and Awakening, it is entirely possible that there will be spells and abilities from DA2 that simply aren't in DA:I.
Six: Spells and abilities. Many of the spells and abilities that did carry over to DA2 were changed in terms of their activation, speed, effects, or any combination of all three. It is more than likely that the same will happen in DA:I, which, again, would cause complications when it comes to fighting.
Overall, it's just not practical. I don't see how BW would be able to do this if they actually were. While it is cool, I just can't see it working. 