Actually, bringing up Missile reminds me of the
other Missile: the one from Ghost Trick, which was another game made by the series producer of AA. It got me thinking, when Phoenix was added to UMvC3, one of his alts referenced Sissel and Lynne, two of Ghost Trick's main characters:
Could you see any Ghost Trick references being added to Phoenix's Challenger Pack? I would love to see something, but my guess is that it would probably stick to AA content. Ghost Trick was kind of in a perfect spot timing-wise when UMvC3 came out -- it was released on the DS right before UMvC3, and the AA franchise hadn't yet gotten into the 3DS games, so Phoenix still only had his classic design.
Still, I would love to see even something small in Smash when it comes to Ghost Trick. I could maaaybe see a single music track (probably
4 Minutes Before Death Variation or the
main theme), or a small animation reference in Phoenix's moveset. For exmaple, what if in one of his moves with Missile, there's a chance of it being the Pomeranian Missile from Ghost Trick rather than the Shiba Missile from AA? Purely cosmetic, but a fun reference nonetheless.
(also play Ghost Trick -- it's got an iOS port, and Ghost Trick's Missile is legitimately one of my favorite characters in gaming)
(Just look at that face, how can you not love him?)