Well if I'm not mistaken, they confirmed both SMA4 and 5. I'm almost positive SMA4 will be a port of SMB3, as for SMA5 I have no idea. What I would like to think is that SMA5 will be a brand-new Mario sidescroller that's been in development since the GBA itself and they didn't want to reveal it because then fans would get impatient. But realistically, I don't see that happening. I hope it's not Yoshi's Story because that's not a true Mario game and to be honest, I think it's a pretty lousy game.
But yeah, I'd love to see an SMB3, and it would be awesome if there were "lost levels." Did they really leave some out? I remember seeing a picture of a grassy level with Para-Beetles, is that one of them? But I would like an entire "Super Players" version of the game. I just hope they don't tinker with the existing levels like they did in SMA1.
Oh and a port of SMRPG would be awesome too! That game is amazing and very underappreciated. And I think that's a game that would actually benefit from adding voices. I'm glad Square and Nintendo are on good terms again. Maybe this means we'll get to see more of Mallow and Geno. Of course, what I'd REALLY like is for the two of them to collaborate on a true sequel to SMRPG for the GCN. Paper Mario was good in its own right but it just doesn't do it for me like SMRPG did.
