I'd love to see more decisions within the story that could branch out the game and add layers of complexity. For instance, decide what to do with Eric. Kill him? Imprison then recruit? Spare him and forget all about him? Or like choose whether Oswin tells Hector about Uther's death, splitting the army but getting a chance to use more of them like in Echos. (Also make Uther playable). I would also love a spy minigame or side plot with Matthew, Leila, Legault and Jaffar. I like the idea of choose your country of origin. That could be fun in a Fates kind of way. I want more Sacae chapters and characters.
If they do end up making a remake, it might not be a bad idea to put FE6 and 7 together, or add playable chapters on Elbert's time with the dragons. A few chapters with Young Athos and Nergal could be cool too. Most folks seem to agree that the balance of the game is what makes it so awesome. That said, I would hate to see a remake as just a replica with better graphics.
Last - let Lyn and warriors use ballistae
