I tried, but in the end I found that I just couldn't care who became Divine, so I decided to play the Inquisitor that way and let the game decide without any interference from me.
The fundamental truth of the situation is that Mage Freedom in Southern Thedas is a lie. The only way Mages could really be free is if the entire social system were reformed to establish a rights-respecting, SECULAR government that secured freedom for EVERYONE. As it stands, "free" mages are simply Mages With Privileges, classing them as Associate Nobles of a sort. Hence why Mage Freedom is DANGEROUS and a "Road to Tevinter". Because the vast majority of the population is NOT free.
Freedom for me and not for thee is and always has been a trap. But fixing THIS situation is not within the scope of the game, so ultimately it doesn't matter which version of privilege wins out in the short term.
The game didn't allow it, but my headcanon was basically that the Inquisitor announced "a plague on both your houses" to all the struggling power groups, washed her hands, and put up a big sign outside Skyhold declaring "these are the appropriate Rights of all persons" and announcing that the Inquisition undertakes to guarantee the free exercise of those rights for anyone wishing to join.
Yeah, go ahead, do your Circle nonsense. Meanwhile, Imma steal all your competent and creative people RIGHT OUT FROM UNDER YOU. It was never established whether the Inquisition owes fealty to Ferelden or Orlais or whether it was an independent polity beholden to neither crown, so I figure I'd just declare Independence while neither country is in much of a position to dicker over it. Ferelden has no heir and I intentionally left Celene, Gaspard, AND Briala alive, so Orlais isn't going to stabilize, either.
Pretty soon both of those countries are going to wake up and realize that their social system has decayed away without anyone being the wiser, while the Inquisition, with its credo of Freedom and Justice For All has become nigh unstoppable.
Oopsie. 