I think what I'd want largely depends on the direction they take with the game. I suppose the most tangible thing I could say at this point would be for the developers to implement mechanics that fit with the narrative, pacing, and atmosphere of the game. Perhaps the best example of this being done well was children in Awakening, and the best example of a mechanic being shoe-horned in for no other reason besides it was popular before was children in Fates.
A couple minor things; I'd like to see the return of weapons with limited uses, the world map from Gaiden/SS/Awakening (I think it helps the player get a better sense of the region this is taking place in), and a greater emphasis on world building than we got in Fates.









