I'm curious.
How likely did you think Chrom was after E3 and did you expect him to be a Roy echo?
I thought he was moderately likely as an Ike echo. I figured it wouldn't be a perfect fit, but would work best out of the potential options.
Roy wasn't even under consideration honestly. At that point, we knew about three echoes: Lucina, Dark Pit, and Daisy. Between Smash 4 and what little we saw of Daisy, most assumed echoes needed to be one to one. Considering Roy had a reverse grip stance, and I thought full animation reworks would be too much for an echo, I didn't consider it.
Chrom himself broke a lot of preconceived notions of what the community at large thought an echo fighter could be, and then Ken shattered whatever remained.