When trying to predict anything Nintendo, you must attempt to think from their fiscal views. Obviously, their goal is to keep the price down, so do not expect a console priced higher than $299. *Had the 3ds succeeded at $250, then we maybe we could have expected a $350 Wii, but that didn't happen*. The good news is, a $299 price point will not affect the graphical upgrade *most* fans are want/expecting. Now, the 4gb xbox 360 is $199... If we follow logic & expect a modern, more efficient, moderate power boost for Wii U, + $50 Upad ($70-75 sold separately), & pack in lite demo game, = BOOM $299.
With 100 million Wiis sold, & more than double wii motes sold, do not expect wiimote+ & nunchuk to be packed in, lets not forget the upad has every wiimote functionality. So, Wii mote+s, nunchuks, and HDD will all be sold separately. The only way I can see the Wii U being as powerful or weaker than the HD twins is if Ninty aims for that $250 launch the original Wii launched with. I don't see that personally, since Wii at the time was a "risk". Fast forward to the present, Wii was a great success approaching 100 mil sold, and folks are eager for a new, HD version with new interface. Folks will pay more. How much? Ninty will find the balance, and $299 seems perfect.
To conclude I'm not worried about the "WiiK" rumors anymore, if by any small chance that happens, then "**** U" I'm just gonna blow my loot on a gaming tablet.