I assume RPG-type games require quite an effort and are a commitment developers aren't willing to take for the GBA. We do have Castlevania, you know, whose heart is in the right place. And I hear Harmony of Dissonance mops the floor with Circle of the Moon.
I think that it is sad that the first post on this fantastic news (if true) has to point out the negatives. Of all the games for the SNES, Super Mario RPG is the one I most wanted to see ported. An informal survey I held said that even those who hate ports would love SMRPG.
Do realize, BTW, that SMRPG is extremely hard to port. It actually ran on what most consider superior hardware. (The cartridge upgraded the SNES to almost Playstation status!) I have heard many people say that a GBA port of the game might be physically impossible. So if Nintendo pulls it off, I'd be extremely happy.