Roserfly

This. Three houses introduced places that are different (although we saw next to nothing about what these countries are actually like) with Almyra being Persian inspired. Brigid being southeast Asian inspired. These are two places that could be very interesting for future games to take place on, and would be an opportunity to experience a fire emblem game taking place in a culture inspired by something that's not the typical medieval Europe we see all the time from several different series. There's A LOT you could do with any non European/Japanese inspired culture for a fire emblem game.

Number 1: Have griffon riders be a thing in future games. Basically what I want is for griffin riders to complete a flying triangle with the other flying classes. Pegasus uses lances, wyvern uses axes, and griffon uses swords. Then it would advance to be falcon knights use lances, and swords, wyvern lords use axes, and lances, and Griffon knights use swords, and axes. Number 2: Customization of avatar character stats so you can personalize them to how you want them to be. Wanna be a magic nuke? You can have those stats. Wanna be a tanky bruiser? You can have those stats. But please for the love of God make sure the avatar character doesn't become a mary sue. Number 3: No gender locked classes. Please they're just so archaic, and unnecessary. I know some classes have lore for gender lock like the Pegasus class line. Even then the lore is iffy at best, and the whole concept of gender lock is unnecessary.