Well, call it Wii-2 and there won't be confusion as people understand its a sequel then. However, if losing the Wii moniker is considered not as important, then a wholly new name would definitely be ok too.
But, WiiU is definitely a little confusing right off the bat as it does not clearly tell the purchaser its a new version. Basically, yes, you will have the same confusion where many people thought the 3DS was just a DS with 3D capabilities.