Not DS2 because it's still very strong and able to do monster sales on every favourable week, be it a big game release, Xmas, any other big sales week, DS fully exploits it.
Not Wii2 for the same reason.
Vitality? Maybe, but' it's more niche than any other Wii device, presenting it as a new platform could risk making its sales results look disappointing.
WiiHD doesn't make sense, unless they simply make a Wii capable of HD output without relying on upscaling, simply an update with 100% bidirectional compatibility with Wii, it would imply a slightly more powerful GPU, simply pumping out more pixels and doing a better antialiasing to make things look smooth even on big HD screens, but keeping the same polygon count as Wii, not changing at all the models of what appears on screen and by no means introducing new games HD-only, incompatible with old Wii, splitting the architecture in two would be a suicide.