I imagine that 16 GB of internal flash storage would be more than enough to eliminate the storage restrictions on the current wii for good.
I also imagine that Nintendo will allow you to use internal HDD, but you, the consumer, muxt provide your own hard drive because Nintendo will not put forth the money to manufacture them. On the bottom of the wii there will be a port where you unscrew a cover and place a 2.5 inch hard drive into the console to boost its memory storage.
What I would like for Nintendo to with the wii 2 is allow what ever storage devices being used to bear the brunt of the files, but what ever virtual console and wiiware titles on the system are still tethered to the console for security reasons. We do not want you to run off and mass produce copies of the files.
Overall, I imagine Nintendo saying, "Here we are with the wii 2. We have heared the complaints of the wii storage debacle from the consumers, so we have provided every storage option for the wii 2. Now, consumers, shut up!"