My guess is that it's the rpg from Monolith Soft. Iwata got them and the guy from SE (Matsumo?) because he wanted a 'Final Fantasy killer' (my words not his) that would be Nintendo owned. IE: He wanted one that would rival or exceed FF and never have to worry about it switching consoles like the FF series did. Probably memory loss factors into the game somehow.
FFVII wii-make would be huge though, and might even eclipse FFXIII in hype factor
FFXIII - going Wii exclusive would be a final nail in Sony's coffin in Japan, but I HIGHLY doubt this will happen for obvious reasons, but that really would make a lot of people cry.
DQ9 - Interesting but no
Everything else mentioned - Too small potatoes IMO