I feel the UOS is the next step for Nintendo. And if they are smart they will put part of it online. I like how the WiiWare keeps track of all the games you have bought...but I think this needs to be pushed further. It should just be called. NintendoWare. And games that are compatible with each system is available to download for that system attached to the account. When you purchase the game you purchase the right to download it to 1 home console and 1 portable device. This means you can build a virtual library that can be with you and be forwards compatible with new consoles and handhelds.
Also, they can retrofit this service and allow those that bought digital games to transfer them into a system...even if they don't have a console currently. That would be a big step to making digital distribution more viable for the consumer.
Now, of course you can have the standard background features like universal Wii Speak Support, Chat, Mii integration for avatars and what not set up in the UOS for the next Nintendo systems...and the UOS once built and updated will be the building block for all future systems to ensure perfect backwards compatibility...and like I said forward compatibility.