Most people know the Wii has simply 'Wii.' It's also Nintendo's most successful console of all-time, so it would be an odd choice to drop the brand and style that made you so successful. Once E3 rolls around, there won't be any confusion that the WiiU is the successor to the Wii. It's a bit different from the DS and 3DS situation, because Nintendo released multiple versions of the DS, but they haven't done that with the Wii.
--
"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."