For some time there have been rumours circling that Apple will move into the console business, of course it is unlikely to be a console as we know them but it will be a console nonetheless.
The rise of Apple as a major player in the gaming world has been meteoric and many feel that Sony and Microsoft are hanging back on the next generation because they need to know what Apple will do. Whatever your opinion on Apple it is hard to deny that they could easily dominate the console market, with the app store they can provide thousands of casual and hardcore games at a fraction of the cost of what they usually are, one man development teams can create hit games and the problems of relying on high street shops that can so easily disappear are gone. Apple are a brand with the money, the know how and the name to get what games they want, how they want and then distribute them quickly, easily and cheaply.
In short, a conventional console would seem outdated when compared to anything that Apple produced and wouldn't have the bonus of other products, such as iPad's and iPhone's being able to directly communicate with them. It is because of this that I think Sony and Microsoft may not bother with the next generation which could easily mean that Nintendo's biggest competitor would be Apple.
Nintendo's next console features a tablet based controller, reminiscent of the iPad and could possibly integrate some sort of app store, a showdown between the two companies would be nothing if not interesting and it could result in a peaceful coexistence or, more likely we could see not only Sony and Microsoft but also Nintendo pull out of the console market and Apple could have a monopoly on the gaming world.
Personally I would embrace an Apple console and would happily abandon my PS3 and Wii for it but I know others would not be so keen. Either way, the next generation could be very interesting.