I don't think the 3DS will limit the NGP at all.
First off, without a price point, we can't assume sale wise, it'll be PSP/DS all over again. NGP, could be the next SNES, in that it being more powerful than the competiton, still out-sold it..
But, the NGP has 3G... I think consumers will notice if they have to pay a bill to T-Mobile that there's something very different about the system..
Also, games on the 3DS pop at you. But, on the NGP, you get to control the game in 3 dimensions (technically, because you're not interacting using the NGP's side panels). But, you have touch screen, and a rear touchpad, face buttons, and dual ANALOG sticks... It's not that hard to figure out which is stronger... Also, remember that first party games will look fantastic... If someone has Uncharted, they're going to expect a certain level of quality from their games, and strong 1st party titles that sell great would force everyone else to get with the program...
But, what that will do is cause companies to cater towards one device or the other, because they are so different... So, ultimately, it depends on how well such things will sell.. So, things wont be limited, they would take advantage of each system's strong points, and probably developed independantly.
But, now that I think about it... All of my PSP games are exclusives (most 3rd party). And, I probably wont get too many NGP games, just a few PS1 classics (mostly megaman) PSP titles, and a couple NGP. I want it mostly for the Music, movies, and internet, to be honest.
