I think Nintendo stands a pretty good chance of having one of the strongest E3 lineups this year. It's now peak software release time for 3DS now that it's in it's prime, so I'm not even worried about that. 3DS software this year is sure to be there, and it's sure to be great.
Wii U is the big question. I think it's 99% guaranteed that EAD Tokyo's 3D Mario is now more than a year into development, so that game could conceivably be out in time for the holidays. At the very least a trailer and game info at E3, even if not playable.
It's more than likely that the rumor of Monster Games making Diddy Kong racing is true, so I expect that to be at the show in full force, with an early fall release date.
Retro's game/games will be ready to show by June, most likely. I'd be shocked if Retro wasn't the studio set to deliver the big AAA holiday Wii U game this year. They've now had at the very least two full years of development time. It's gotta be getting close to being finished, whatever it is. My money is on a reboot of Metroid, not necessarily a continuation of Prime.
Zelda is the big question mark. No question on the 3DS side, Grezzo by this summer will have had two years of development time to make whatever it is Nintendo's had them make. My guess is either a remake of Majora's Mask like they did with OoT, or perhaps they're assisting with development of a sequel to Link to the Past that Miyamoto keeps hinting at. Maybe both? Either way, they'll have a Zelda for 3DS by Christmas for sure. But still the big question mark remains... will Zelda Wii U be in a state that they can show off polished graphics and gameplay details? At the most, the game is barely a year into development. I think maybe a trailer with no playable demo is the best we can realistically hope for at E3. It's probably not going to be done until late 2014.
Smash Bros. of course is the one everyone knows will be there, so it's just a matter of when Nintendo will be able to have it ready. A playable demo and a game nearing 50% completion wouldn't be too unrealistic. I'd say it gets the full unveiling at E3, both for Wii U and 3DS, and gets a spring 2014 launch window.
