This has been known for quite a while now, since like E3... or even earlier I think. :/
Also don't see why it matters. People who have ethernet only are dumb. lol jk. but seriously.... who doesn't have Wifi in their home now and has internet?
Plus the dongle is already confirmed to be the same one on the Wii (so those previous wii owners are covered) or just pick on up for cheap.