Nintendo World Report's staff offers up their expectations and hopes for this year's E3.
I expect that Nintendo will continue to roll out the casual gamer bandwagon, while throwing a few scraps to the hardcore crowd. I see Nintendo announcing more DS peripherals and debuting greater DS/Wii connectivity. I can see the DS being in the spotlight of the show with a possible redesign. Likely Nintendo will remove the GBA slot, slim the unit down, and make the sound better; an overall improvement of the unit.
We may also catch wind of a new Zelda game and Metroid "Dread" might make a hinted appearance.

I think Nintendo is going to underline their numbers (so is everyone else), then USE those numbers as an excuse to not do anything about their online problems. Things like "well, people seem to like Super Smash Bros. Brawl--it sold a gazillion copies despite the online shennanigans--so we're not going to do anything about it." The continued shortage of Wiis will be addressed in a manner that's been addressed in the past. Namely: "We know there aren't enough units. We couldn't be happier. We're trying to increase production by the holiday season."
What would I LIKE to see? That's easy. I'd like to hear Reggie tell interviewers that Brawl's online shortcomings are realized and are being fixed in some fashion ... but he won't. If anything, he'll evade the question. I would like to see a REAL online strategy for playing Wii games. Like automatic Friend Code updates or, dare I suggest it, the abolishment of friend codes altogether in future Nintendo games. I'd like to see more old-school revivals on WiiWare (Mega Man 9 is a great start) as well as better Virtual Console games.