Well, while we didn't get firm dates, weren't both Paper Mario and Luigi's Mansion announced as Fall releases? I realize that's not a clear answer, but it appears to me that those are the 'big' Fall 3DS releases, so I'd guess Luigi in October and Paper in November. That makes them far enough away from NSMB2, not on top of each other, and with a lot of shopping time before Christmas. That's just my guess, anyway.
I'm hoping Animal Crossing makes an appearance in the next conference, though I'm worried it's been quietly pushed to 2013. I hope I'm wrong on that, though.
Fingers crossed for a surprise Layton announcement for a September release. The last two games were both late August/early September, and it's a niche enough title to release a month after NSMB2.
I'm just guessing, or hoping, anyway... I mean, NSMB2 in August, Layton in September, Luigi in October, and Paper Mario in November sounds like one hell of a Fall line-up.