Nintendo generally follows the rule of "feature a game at E3, it's out by next E3." It gets broken occasionally for delays (Metroid: Other M) or big productions (Skyward Sword, almost every Zelda game ever). Following that logic, I'd be surprised if Luigi's Mansion 2 isn't out by E3 2012. I think it is the next major first-party release in North America, likely coming out in April or May.
If it misses that, it is delayed for some reason or another, which is of course a possibility.
Also, while Paper Mario and Animal Crossing have been at the past two E3s in trailer form, they've never been featured. I'd expect one or both of them to be a focus of Nintendo's 3DS line-up presentation at E3. Mario Tennis, from the harder note of the 2012 as opposed to Paper Mario and AC's "TBD," might be the summer game.