Yes, the thing about the Fire Emblem delay that confused me so much was the fact that virtually nobody was talking about it after the E3 Direct. It seems like almost all the major media outlets completely forgot that they announced this game over a year ago and it was supposed to be a 2018 game. When I was watching the Direct live, I was really liking the trailer and then at the very end they say "2019"; it felt like a slap to the face. But afterwards, nobody seemed to say a word about the new release date outside Fire Emblem fans, as if they didn't even know it was already anounced for 2018. This game, even without Yoshi's delay, is the main reason for the lackluster second half of '18 Nintendo has had. They were likely banking on it to help them this year, along with Yoshi, and neither of those happened. These delays also explain why it seems like we know most of the 2019 games already. IS hasn't said a word about why it was delayed (I mean, they have no reason to do so, especially since pretty much nobody is criticizing them for it).
That whole FE situation is weird in general, and could be a sign that something is up at IS. But it begs the question: if not Advance Wars, then what would IS be making? Another Pushmo or Codename: Steam? I really doubt it. I suppose there could be a new IP in the works, but after Codename: Steam didn't sell too great they might be hesitant to try that again, especially since FE has been making bank. So other than a new Advance Wars game, if IS is actually working on another project as right now, I think the biggest possibility is another FE remake, like SoV. There's a lot of people that want remakes of Genealogy and Binding Blade, especially since those are currently JP-only games (so they'd be like brand new games for many Westerners). But at the same time, why do these now? I feel like they'd want to finish Three Houses first, and then perhaps use that engine to make a hypothetical FE remake. This is in line with what happened on the 3DS, where they made Awakening and Fates first and then did SoV. Given all of this, if IS is working on a project simultaneously with Three Houses, or maybe if a new project was just started recently and perhaps contributed to the Three Houses delay, it could very well be a 2020 Advance Wars game. The big question that remains on this front, though, is whether or not IS even wants to return to Advance Wars. If they do, now would be a perfect time to do it, especially since Advance Wars would work so well on Switch. You'd have the handheld aspect that helped make the original games so appealing, and then you could hook up to a TV to play locally with friends on one big screen. COME ON IS DO IT