Wii+ phase-in...
-mid-generation bump
-same Wii casing (different colors available)
-cheaper, lower wattage, cooler motherboard/chipset
-boosted flash storage and higher download cap for WiiWare titles
-boosted RAM and/or frame buffer to allow 720p native ouput
-software upscaling of new/current games to 720p
-WM+ packed-in
-WiiSpeak packed-in
-component cable packed-in
-32GB SD Card packed-in
-WiiSports + WiiSports Resort + Wii Demos all on one disc
This would work for a lot of people without being too unrealistic. It's basically the current Wii with more peripherals packed-in and native 720p output. I would harken it to be much like a DSlite to DSi transition. However, there are some issues with this...
Issue #1: would Nintendo be able to boost the frame buffer so easily...and even so, what about current Wii owners?
Issue #2: current Wii owners' save data (especially for WFC data/VC/WiiWare) can't be copied to a new Wii...if anything this could make the already poor WFC issues worse. This could be fixed by allowing tansfers between Wii to Wii+ via WiFi & product registration, but that could backfire...
They could answer both those issues with *Reggie*Not*My*Problem*...or, they could just wait 'til the next system and not do a mid-way jump. I thought maybe a Wii "expansion pak" could be done via the USB + A/V output, but that's less technically doable. More realistically, Nintendo stays and milks the current Wii and simply does pricedrops, pack-ins & new colors for the next couple years instead.
WM+ would be the perfect oppurtunity to finally offer another Wii sku (though I do think having only 1 sku for the Wii helped it) and/or phase out the old one with one that comes with WM+, WiiSports Resort (and to be sweeter: WiiSpeak, component cable & an SD card) packed-in.