Can you really imagine combat as the Inquisitor without the Anchor though? That would feel a bit weird to me.
Though if the dual protagonist thing is really an option, perhaps the Inquisitor could gather information and choose what missions are taken and the other main character would carry them out. Not sure if that would feel confusing to brand new players though.
**complete unrelated side note: If bearing the Anchor convinced most of Thedas that the Inquisitor was the Herald of Andraste, what the heck does losing it mean?
Sorry to butt-in out of nowhere but I just fell on your comment and felt like voicing my opinion.
"Can you really imagine combat as the Inquisitor without the Anchor though? That would feel a bit weird to me."
Hell yes. Gameplay opportunity. Give me an interchangeable arm (ever play Kotor 2? Check out bao-dur, except instead of his arm being only used for disabling shields it could be constantly modified and employed in different ways depending on your class).
Now add that to replay value and strategy flexibility. Even add crafting and modding to that arm. It could be a refreshing change to the franchise in terms of the dynamics involved in and out of combat. It could justify starting at low level. Hell, you could even start the game with it just getting crafted and explained by Dagna (for the benefit of the player to learn new mechanics as well as for the narrative implications). Just look at Metal Gear: Phantom Pain
"**complete unrelated side note: If bearing the Anchor convinced most of Thedas that the Inquisitor was the Herald of Andraste, what the heck does losing it mean?"
Since the game will mainly be in Tevinter (I'm assuming), it mostly means nothing because we won't be dealing with the fallout. Besides, playing the Herald angle was a choice, so I doubt they'd play into it much in DA:4 (if the Inquisitor is back as a playable character).
Anyways, given the events that transpired with Solas and the choices which were allotted to us (redeem or stop Solas) and the end scene that follows (gathering our "advisors" i.e. Leliana and Cassandra while saying we'll need to find new allies), in my opinion it would be completely illogical not to follow through the narrative they've just set up in a very grand yet personal way (whether you cared about Solas or not). It would also be a missed opportunity.
Just because you'd reuse a protagonist once that doesn't mean it has to limit your exposure to the world. The setting alone (Tevinter) would be enough in terms of exposition and world building. Once the narrative arc is complete, then you can move on and move forward further in time or place. What matters is the decision that makes the most sense for the story. What makes the best game possible. In my opinion that's moving forward with the Inquisitor and new followers, there's just too much to take advantage of, both in terms of gameplay and narrative.