Whether you hate or love Anders, i think we can all agree that he is a pivotal character, the one that sparked the fires of War.
Assuming he has been spared at the end of Dragon Age 2, it is stated by Varric that the other mages ressented him for throwing them in this war, and he had to leave.
So he would appear he is now alone.
I can't lie, i was hoping for a quest to find him in Inquisition, just to see how much he would have changed (if he only had). And also, depending on his persona, whoop his ass.
One thing reignited my hope for his future appearance, though it would be kind of a stretch...
And it is that concept art for Inquisition:
This 'hermit' wear a mage robe similar to the one Anders wear. Since Inquisition, though, this is not so rare (Imshael, and other Mage NPC wear it as well). So the uniqueness is dropped down.
The second clue toward this hermit possibly being Anders is the hair colour. The desertic setting seems to indicate the Anderfels, the homeland of Anders.
Finally, though it's really my two cents, the missing right arm. The arm that held the staff, which sparked the explosive mixture in the Kirkwall Chantry. For someone like Anders, steeped in Justice and Punishment, i think it's fitting to see him chop his own arm off, a self-imposed punishment for all the dead he has caused (or simply to bite off some of the influence of Vengeance)
Of course, it could also be a third party that chopped his arm and not some kind of penance for his deed.
Since Inquisition is all about cleaning the mess and not hunt and punish the responsibles (as stated by Cassandra), it would seems Anders will have it easy for the time being.
But what will happen it the future? Once the war is stopped and nations resume their petty wars? I'm pretty sure there will be someone to hunt those that started it all. May well include a Pro-mage Hawke in this list.