To be honest, I'd prefer a Thedas: Total War to more Warhammer titles. The Warhammer ones are all way too magic-ey for me - the giant beasts and monsters totally throw me off. One set in Thedas, however, would have a solid basing in 'real' medieval tactics, but you'd see the way the various factions used (or countered) magic.

There would also be a ton of interesting campaign possibilities; playing as the Inquisitor, Gaspard, Celene, or Corypheus around the events of Inquisition would be one, as well as one set in the time of the Orlesian invasions of Ferelden, or one in the Exalted Marches on the Qunari.

Man, I've got shit tons of ideas for how the various factions would have their units and fighting style set up. I see Ferelden as closer to medieval Scotland, though. Mainly focused around pike units, supported by crossbowmen, mabari hounds, and some limited cavalry, with some bonuses for raiding and penalties for enemies moving on their territory. Chantry units, like Templars and Circle mages, could only be used in wars against non-Andrastians - the Avvar, Dalish, Tevinter, Qunari etc.

Perhaps you could even start up your own Chantry, with some sort of Anti-Divine, and therefore allow you to use 'Chantry' units, but at the cost of having others use them against you. Regardless, Total War: Thedas is the dream.