I think in several years, we'll potentially see game consoles engineered to specific specifications, like television broadcast signals. From there, console-makers will create their systems with unique feature-sets, like the ability to pause at any time, specific types of memory, saving replies/video of any point in the game, and the like.
Companies can also create other hardware, different variations of controllers, and such, but the base hardware that plays the games will probably become an industry standard, like DVD, USB 2.0, and the like, approved by video game boards composed of various publishers.
In this sense, Nintendo may be ahead of the game, considering the Motion+ and Wii Balance Board as "base" hardware, itself.
So, if you want to get into games retail, you'll likely buy a license to play the game, like on the PC, either in a store or online. The purchase of the license will allow you to play any iteration of the game you can possess, but only on a console that has the license. Virtually the same as how it works on the PC.
I'd predict not next generation that someone will begin to dabble it, and license out their platform to different manufacturers, rather than manufacture it themselves, once they figure out that the hardware can cost too much to make in a way the consumer would like it.