But its likely that they will show at least one new game from Nintendo that uses MP extensively. A killer app so to speak. Whether is a casual or core title its up to Nintendo to decide, but I think it might be a core title because casuals already have the MP killer app (Wii Sports Resorts).
It'll be Star Fox White Water Rafting Adventure, to continue the trend of crappy Star Fox games that completely negate everything that anyone ever liked in the series. In the game, the Star Fox team will be on vacation on a sunny mountain retreat, so we'll have our obligatory minigames. The centerpiece of the game will be the WW Rafting experience, where players use the Wii Motion+ to paddle their canoes down a river...only nothing they do will actually matter because the raft is being pulled along by an Arwing via a tether. Other events will include a hiking adventure where everyone runs around the woods on foot, and there will also be a mode where you fly around the mountain range in the Arwing trying to save Slippy from a bear, which will be approximately 10 seconds in length and revolve entirely around flying through a single ring.
Oh I kid. Actually, I do think we'll hear something about Star Fox at E3, if only because it's one of the few semi-worthwhile franchises Nintendo has right now that they haven't done anything with in a while. Honestly, I'm thinking now would be a good time to see some early footage of Zelda Wii with Wii Motion + action. It would fit the standard Nintendo Zelda-trickle, where we see bits and pieces of the game about 3-4 years before it actually comes out. More realistically, I expect we'll see a Pokemon game for Wii that may or may not use Wii Motion +...but once again it wont' be an ACTUAL Pokemon game because that would make too much sense. Instead, it'll be another Stadium clone.
Oh, and naturally DSi will have a decent showing. But the biggest reveal of all will be the massive amount of money Nintendo's been making, as shown via mountains of flowcharts and graphs on Powerpoint Presentations.