It is very simple really.
This generation Nintendo cannot add HD gaming to the Wii.
PS3 and 360 will have motion control by the end of 2010.
So if the addition of motion control narrows the difference in sales between the Wii and either the 360 or the PS3 then MS and/or Sony will be satisfied. If they start selling more then they will be thrilled. Even if at the end the Wii has more sales the addition of motion controls to the PS3 and/or the 360 will be nothing but a success.
Only way for Nintendo to add HD gaming is to release a new console. That doesnt mean all the casual Wii owners that jumped into gaming for motion control move to the WiiHD. They may never move or they may look at what else is out when they are ready to move. Key is that these new game console owners may purchase differently, I expect them to not upgrade to the next gen nearly as quickly as the more traditional gamers. Not to mention if Sony and/or MS release at about the same time you can be 100% sure that the next Nintendo console wont be as powerful so Nintendo better have something disruptive ready again.
Its libraries that sell systems not a single game.
