You really think mages won't have plenty of straight-up damage available?
What makes you think that Easy won't still be easy?
Well, for instance the combat with the Arishok on DA2 comes closest to this 'damage mitigation' and tactics I am reading about. My strategy was to not get hit. When i was hit, (because mistakes happened during combat) I used potions to heal as I ran around the room in circles, staying out of reach, firing off spells, arrows at him pelting down his health. That was not an easy combat, even on the lowest setting. I died several times before I finally figured out what I had to do.
I am imagining combat in Inquisition being similar, with debuffs on mobs to slow/freeze/paralyze them, lower attack power etc. Warriors will have abilities similar to Aveline's 'oh sh*t' skill where she hunkers down and minimizes damage receive. Rogues will have some type of evasion I am assuming since they do best in lighter armor. And all classes have runes to--not really sure what those will do, but I imagine it's to help in fights (like a fire resistance rune to use in a fight with a dragon). And, kiting the mobs around the room when all else fails.
Since healing is extremely limited by your resources vs your mana pool, it's already rendered extremely difficult, even in easy mode.
This is why I think 'easy' won't be 'easy' anymore, but rather easy is in comparison to 'not as hard as nightmare-mode'.