Looking at history, when they have a dominating presence they typically keep the base name.
NES/SNES, Gameboy (used a lot), DS (used a lot), etc.
So, since this will be following the massively popular Wii, they will want to build off of that familiarity and built in name recognition.
So, I would expect something that signifies it as a Wii child as well as incorporating the next big feature.
It wont' be WiiHD as that would make people think it is the same with only HD and Nintendo has repeated many times it needs more than just HD.
It may be Wii(pluss symbol) as they seem to like that and it could incorporate any additional features.
It won't be Super Wii as that is of a past era.
It could be somethign related to a more robust online relationship, like Wii Life or Wii 2.0
It could also simply keep the Wii name as is, just like iPod and many other familiar devices get a new generation but don't change names at all. In fact, I see this as the more plausible choice as it keeps simplicity and familiarity and relies on Nintendo's excellent marketing to drive home the new experience.
