This is just my prediction for the next FE Echoes remake. I have no idea whether or not this will be true but here goes nothing.
As much as I want FE4 to be remade I'd have to say that the next FE remake will be FE6 and 7 together because you can't have one without the other. FE7 is the prequel to 6 and 6 never made it outside Japan and that being the continuation for the story of FE7 I would only see fit that both of them get remade maybe not on the same cartridge but considering how FE 3 have both a remake of FE1 and had the sequel on one cartridge, its a possibility.
So, why FE6 and 7 you say? Well, I've been thinking. You know how Awakening and Fates both had an avatar, pair up, the marriage system and Risen/Faceless. Shadows of Valentia has no marriage system, no avatar, no pair up, but has Terrors. So I've been thinking that IS is just taking a break from the marriage system and just giving us the core Fire Emblem gameplay without having to stress about who are we going to pair up in battle and who's a good mother/father for this particular child character. We are just playing the core game for awhile, and I think that FE6 and 7 are coming next simply because of that. But as for the return of the avatar, I'd rather him be a silent protagonist like Mark in FE7 but still no marriage system. I mean, I haven't payed all that much attention to other people's opinion on their view point of the marriage system as of today but I think we need a break from it and just play Fire Emblem for the strategy and not the child rearing. BUT after FE6 and 7 comes out FE4 and 5 come next with the original marriage system (at least in 4) and child characters that fit perfectly into the story. I think IS is just letting things stay familiar and not letting things like the marriage system and the avatar go stale where to the point that no one wants it to return. The marriage system and the avatar will return later maybe not in the same game but will separately for sure. Like FE7 for the avatar and FE 4 for the marriage system. It's just splitting things up to keep things fresh. But who's to say these two won't appear together in the upcoming FE Switch?
What are your guy's thoughts on this?