Honestly, Echoes deels like such an incognita because we have no idea what IS is gonna do with it: they can do what they already did before and just update graphics with some small differences here and there or actually put an effort into it and make Echoes the HGSS of FE.
Map design needs to change, like, seriously, open maps are one of the reasons I find Awakening boring.
Trade should be implemented too, no need for shops since weapons are infinite use but a simpler way to exchange items between units would be appreciated.
And the one thing I hope they add is a postgame. Gaiden inspired SS in a lot of ways so maybe they can do the other way around, because even though SS was easy, it still had a great postgame challenge(and another one on the easier side) and gave you something to do with all those grinded up units, I really feel like it would benefit greatly from having something like that. Hell, Gaiden already has a bunch of monsters they can use as the enemies for it.
Just hope they keep the Magic system because I saw some footage of Gaiden and a healer was casting Nosferatu with no HP cost lol