"Another factor I see is the growth of tablets. Schools are starting to use tablets such as the iPad. Parents are buying their kids iPads and iPod touch in lieu of gaming systems. I think buying an iPad which can be used for productive activities is more palatable to parents than a gaming first system."
Not sure about the iPad, but the iPod/iPhone have limited gaming potental do to the lack of buttons/screen real estate. Only a handful of game designs can work well & could they quickly get played out in a few years.
That being said, I don't know how the NGP is going to hold it's own given the reasons that Happy Squirrel laid out plus the fact that the portable console market is likely to shrink in the future due to Apple/Android devices. Nintendo is taking it's chances with 3D, where is Sony going off to?... a system that looks to be supported almost exclusively by direct console porting.
