I think a remake combination of the two games would be amazing.
Saving Lives - In the kids run, parents are either do old, ill, or dead to help. Like Eliwoods wife who died several years before the game starts if memory serves. But give us a chance to save some of the old characters like Jaffar/Nino
Also. Tactician. Give us our own personal character. (Why do you look like Marc/Morgan? HMMMMMMMMMMM!). Add new child unit for our Tactician and have them meet an unfortanate end between the two games where their kid becomes the new tactician for the army.
More supports. Some chars deserved endings and supports with one another. While we know guys/girls wanna talk and hook up, i want to see same gender convos as friendships deepen. Come on, who doesnt want to see Maribelle and Tharja supports? Or Lyn wanting to spar with Karla?
The tricky part would be the kids themselves. Would they stay 'true' to the games or change classes depending on mommy and daddy? I mean how the hell does hector produce a mage?! Meh...take this with a grain of salt though.
FE6 Characters - Another tricky thing. Do you simply make some of the characters introduced related to the previous cast or introduce new kids to run around? Thats a lot of characters.
Awakening Kids- Why the hell not? We already had three jump to a different world. Cynthia, Kjelle, and Gerome would make good guest characters.