Well, I don't think the NGage will take-off as a Game-machine simply because of these facts
1) the price is unreasonable high it will be at least 2-3 times higher than for it's competitor the GBA (which also does 3D)
2) technically the NGage is of a lower quality than the GBA (lower res screen, fewer colors, lower spec sound etc.)
3) the controls are abysmall, the design of it is simply put awful
not to mention that it will probably go the same way as the Nokia 5510 (I think) you now the Youth phone with radio built in (nobody bougt that one)