-Completely new universe. No references to past games in the series unless it's DLC. Fates kinda failed at this with its optional content.
-Lower stat growths, not like what Awakening had.
-A reasonable level and stat cap. Awakening had stats that capped at 60+, which could only be reached if you grinded. Fire Emblem is a SRPG, not a JRPG. Enough with the grinding, it takes away the feeling of strategy.
-No more fanservice. I mean I guess it was okay for Awakening seeing as how it was an attempt to revive the franchise, but don't do it anymore.
-If there's going to be second gen characters, there better not be anymore time travel or alternate universe garbage.
-I would like for Arenas to return, although to prevent it from being abusable, it should be done in FE4's style.
-Better AI, the enemy units should acknowledge the Weapon Triangle. Enemy units also shouldn't need to resort to attacking whenever the see the chance, that's suicidal.
-Better written plot and characters. Don't make them so one-dimensional.
-Better map designs that add strategic value. Really disliked Awakening on how 90% of maps were open spaces.
-Limit each units' support choices in favor of better quality writing. I don't care if a unit only has 2-5 support options, if it can't be written well, you might as well shouldn't do it.
-Pair up could be kept, although it should be made so it isn't a broken mechanic.
-If there are customizable Avatars, there should be ways to change their personalities and skin tones.
-There should be variation in mission objectives, not just routing the enemy.
-Ballistae and Fog of War would be nice to return.