On the Wii core userbase statement:
According to last Nintendo survey the "core" (male 14-24) userbase is pretty healthy on Wii anywhere outside Japan, in line with DS "core" audience. Japanese Wii demographics is based around kids+parents userbase, while in US and Europe there're a decent amount of young male audience. Though those, maybe, aren't exactly owners of the Wii (e.g. mom bought it for Wii Fit), but they have access to the system, it's in their households, so that's no big deal. The big deal is to convince them to buy games for Wii.
//The problem with "core" lies in old game development\publishing paradigm. Obviously Wii isn't the best choice for multiplatform games. Graphics as the top selling point of numerous games that appeal to young male audience is the weak point of Wii (not to mention a lack of effort from third parties, that leads to less content, less features, weak online etc., but even with good ports... sorry, not gonna work especially well) - people definitely will choose HD-version over Wii-version (could be some other secondary reasons, like constatnly ignoring Wii won't help third parties build up it's fanbase on this platform - heavy marketing needed, that leads to extra money; not to mention overall bad image of Wii among young male audience).
Disruption of this paradigm was one of the main puproses of the whole Wii campaign. Porting on Wii from HD-consoles won't work, so don't even bother. People need some extra selling points, extra features (obvious but not single option - controls) that could have convince them buying Wii-version over HD-verison... or even better - Wii exclusives. There're some good examples of this simple idea working with so called "core titles", but not too much.
For now many publishers stick to the idea of development of games with more broad appeal (mini-games, copying Nintendo efforts, fitness games etc.). They will flood Wii with such games, and this not gonna change anytime soon as long as this paradigm works, not until oversaturated market of casual games will crash and their profits are down.