Based on historical figures, I'd say your conclusion is far from certain tom. Hardware and graphics alone will not cause the NGP to sell more than the 3DS. You can just take a look at the sales of the DS vs PSP, or, if we move out of the handheld realm, the Wii vs Xbox and PS3. In both cases, the weaker hardware managed to outsell the stronger one by quite some margin. The Xbox and PS3 have only recently started outselling the Wii on a yearly basis, but on overall sales the Wii has still almost outsold the PS3 and Xbox combined.
I would say that I personally would wish Sony more luck that Nintendo. Nintendo needs a stronger competitor, because at the moment they can ship units like mad just by releasing a new version of Mario/Zelda/Metroid/Pokemon. I think a more significant factor will be price. To the average parent who actually has to go out and buy one of the two, I'd think that a lower cost would be the most desirable, not the shinier screen.
To be fair to Nintendo, at least they do try and be innovative with their hardware (if not exactly groundbreaking in terms of power).