32 and 64 GBs sounds way too big for the Wii and will probably be too expensive as well. I could see them putting a HDD size of no more than 20 GB at the most.
Then again this is a rumour so this might not be true anyways.
Generation 8 Predictions so far.....(as of 9/2013)
Console that will sell most: Nintendo Wii U
Who will sell more consoles between Microsoft/SONY: SONY