Wii Sports Resort will DEFINITELY be shown. Whether the hardcore will whine about it is up in the air but it's got the 1:1 swordfighting everybody's been asking for.
I think the long drought is evidence that Nintendo is indeed making more complex titles (I'm not sure I'd call them core, I wouldn't be surprised if they're the beginning of the "new core", more complex and game-ish games made using the Wii's primary values rather than old core game designs with some Wii controls shoehorned in) but again it's uncertain how people will react. The WMP will probably be the focus of the show with almost all new games demonstrating different uses of the thing to really hammer the point in that the thing IS the HD Wii upgrade people have been asking for (it just increases the definition of the controls instead of the graphics) and that it's really a must-have with awesome software that everybody wants. I think Nintendo has really been holding back on announcing WMP games so far, their only announcement was Wii Sports Resort but I doubt they'd support the WMP with only one game since third parties really can't be trusted with that.
Last E3 Nintendo showed the hardware to preempt hardware whores from heaping praise on the competition should it decide to unveil its own Wiimote rip-off, this E3 Nintendo will show the software to really drive the WMP and simply crush all opposition that might arise under an onslaught of software that cannot be matched. I mean, think about it: Had MS or Sony gone in with a Wiimote clone (obviously with a gyroscope included as it's more feasible now than back when the Wiimote was created) and a few games last E3 they could have hit Nintendo during a drought and potentially delivered one or two killer apps to establish their own position. This E3, if Sony or MS try to go in with a Wiimote ripoff, not only will they have to face the technologically upgraded Wiimote so they can't promise better motion controls, they'd have their few games that they could prepare until now go up against a full volley of games that probably had more dev time, more experience and more sheer numbers. Nintendo can commit fully to the WMP since even gamers without one could use the fallback option in games that provide it as the Wiimote can at least approach the WMP's features. If MS or Sony committed that much* they'd risk splitting their market, their default controller cannot be a suitable replacement for their Wiimote clones, they cannot bundle it as easily because it's going to be a lot more expensive than a little dongle that plugs into an existing controller. Sony and MS would have to divide their attention between the new and old controller. Sure, they could say "screw the old way, we're replacing our controller completely" but their userbase would scream bloody murder and I'm certain they don't even WANT to do that. This isn't a PS1 controller upgrade, they can't add fallbacks, it's all or nothing.
This is a step of the disruption, going upmarket. Nintendo wants to take Sony and MS's territory but on their own terms, not on theirs. As such the development must be games that appeal to the people who currently make up the core market to siphon them away yet it must do so in different ways or it's facing a straight power struggle between the incumbent and the disruptor and that's not a battle the disruptor wants to fight. This is blitzkrieg, not attrition. People are right in that Nintendo is behind in the core market, that's the point. They cannot fight MS and Sony head on in the core market. However there is only a core market, not a core gamer. The gamer is in whatever market appeals to him and by creating a different market that also appeals to him the gamer can be conquered without ever setting foot on the core battlefield.
Yes, that came out longer than I thought but by following these thoughts I further my own understanding as well...
*=leaving aside that both have less development capacities than Nintendo