I don't think Shulk is a shoe-in, but I personally consider Chrom as one. I've never played a Fire Emblem game so I have little basis on... anything, but then again I can use my little knowledge to make a statement that Chrom is actually a character which not only is a main character in Awakening, but also interests a non-FE-fanatic like me the most. It's not really a thing of uniqueness, since anything can be made unique, it's just a thing of image and recognizability. I'd presume the "poster boy" -image he seems to have may attract many gamers who are not familiar with Fire Emblem, sort of like Marth did in Melee, and also gives him an edge over other seemingly popular choices (Lucina and Avatar/Robin I guess?). But maybe that's just me. The Fire Emblem fans are very dedicated to the series, so hopefully I won't get much bashing when I state that Chrom is one of the characters I truly believe is a shoe-in (the others being Palutena and Mewtwo - all other characters' inclusion I see as up in the air still). Call me surprised if it doesn't happen haha.