See my "wish" stage list is different than what I actually expect to see. Which is why chose a stage such as "Phaaze" over "Skytown Elysia". I have reason for every choice I made. I'll explain the Fire Emblem choice.
I chose "Akaneia" [sure I'm spelling that incorrectly] as the new Fire Emblem stage because of the recent remakes of Marth's series on the DS. Not only that but Akaneia was a planned stage for Melee, but dropped for whatever circumstance. It is likely whatever they did plan was likely integrated into Castle Siege. Still, knowing that the idea was there at a point I think they could revisit it given the circumstances.
I don't know much Metroid Prime so O.K. I guess.
As for Dragon's Altar, I guess you're right, besides I doubt Sakurai is that creative. XP
But my only thought is that Castle Siege may have been Akaneia in Melee, why else was it one of the 3 stages to be completed by E3 06? I think Sakurai had the stage already in mind.
Oh well, at this point I'd be just happy with any FE actually based off a FE game, and at the moment I think Marth's games are the best and mostly likely choice to find one.
Plus Castle Siege borrowed from all the World Wide FE games primarlly (trust me as a FE fanboy) so it would make sense to have a FE1-3/11-12 stage.
I'm all ready past the point I wanted to stay up (got too busy with my new avatar). Night.