my theory is to have a good e3 you need 2 things
Eye Candy
Genre Coverage
Nintendo has only provided Eye Candy in the form of Mario and Zelda
Genre Coverage
The Last time Nintendo had coverage of every genre was like 1998, they had fighters, shooters, surivival horror, rpgs(well Aidyn Chronicles ended up sucking hard), racing games.
Actually Wii had pretty good coverage on everything but Shooters, which ironically in the n64 days Nintendo was the only one who really had those genres covered. Stealth action wasn't really a genre people cared about in 1998 until MGS came out, and there was no Sandbox Crime games.
Heres What I hope happens
Resident Evil game
Square Enix RPGs
Sega support
Unreal, Valve, id, and Crytek shooting games
Konami's Fox Engine running a big Kojima Game
GTA
Activision and Ubisoft already support Wii U..so that's good.
Mass Effect
Mario and Zelda
sounds ambitious, but all these things are actually pretty likely. Very few of those would make the launch window. The Kojima thing, and id support being the least likely.
Also, despite Nintendo usually releasing in September-November, i've heard rumors they'll release at the end of August, which I could see as being a good time to launch. Its after e3, so it isn't long after the hype, but it isn't too long before the holidays, so it gives the fanbase some time to grow before that. Its also 3 months before november, so it will give time so that the people who have it fall in love with it and show it off to everyone who doesnt quite get it.