I figured, as the resident Chrom Guy™, I'd give my input on the idea of an Ike Echo Chrom. Up until now I haven't said much on the matter.
In short, Echo Chrom is a toss up. On the one hand, we already have a lot of Fire Emblem characters, including an Echo (a Fire Emblem echo from Awakening, even!). As well, Sakurai envisioned Chrom as Marth and Ike's middle ground, so shifting him completely to one side of the dichotomy may seem suspect.
On the other hand, Chrom was someone Sakurai originally wanted in, and someone who he knows is popular with the fans. And if you subscribe to the "Mii Costume = Consolation Prize" theory, he may have even done well on the ballot. And he's still pushed pretty often by Intelligent Systems to boot.
As well, it's possible Sakurai may reconsider how he originally saw Chrom due to Heroes. If you weren't aware, in Heroes, Chrom is part of the Mighty Glacier archetype, unlike in Awakening where he was a Lightning Bruiser (to use TVTropes terms). He's even slower than Ike is there. And one of the moves that Ike had that didn't fit Chrom (Up Air) actually got changed, to boot.
The only move of Ike's that REALLY doesn't fit Chrom, in my opinion, is his jab. Chrom would more likely incorporate a shoulder bash than a kick for the second hit, but maybe that's something Sakurai would be willing to overlook. Some of the throw animations are sketchy as well, but I digress.
As far as Specials, Eruption would be replaced by a move called Awakening. This would be based on the rite that gives his game its name, where Chrom was bathed in Naga's holy fire to become worthy of the Exalted Falchion. Chrom is already the type to stab his weapons into the ground, after all, and the only change that'd need to be made is making the flames white to signify that they're Naga's.
Quick Draw could stay as is, but be renamed Luna, as the animation for Luna is basically the same. Maybe Chrom's could be differentiated by being able to go through opponents, like Luna can in Awakening.
Counter can stay because lol Counter.
Aether isn't a big deal either since A) Chrom performs a similar move when fighting Lucina in Arena Ferox, and 2) Chrom naturally learns Aether in Awakening (and Heroes, too). This might be too big of a change, but if not, maybe they can make the descent of Chrom's Aether angled as it is in Awakening. But if that is too much of a change he can be kept the same as Ike's.
Final Smash can be a Pair-Up styled move with Frederick assisting Chrom, since that's incredibly in-character.
But in the end, while I think it's TECHNICALLY POSSIBLE Chrom could get in as an echo, I'm not getting my hopes up. I learned that lesson four years ago and would rather not need to learn it again. But if it did happen? Well, I'd finally have playable Chrom. Of course I'd prefer a unique moveset, as I've made many for Chrom in the past, but Sakurai disagrees so it's not worth complaining about at that point. And being able to play as Chrom, my favorite Nintendo character? It would truly make the game Ultimate for me.
