I speculate it won't happen. I expect them to improve their selection of iPod/iPhone games incrementally over the years. There's already a dozen or so of games for iPod Classic/iPod Nano and there will be games for the iPod Touch/iPhone this year.
Some remarks.
1. Why talk about the future, let's look at what happens right now. The iPod touch and iPhone are set to turn into a gaming platform in a few weeks (Apple announced it for Feb, but seems push it back to March). Apple is going to release an SDK for their Mobile OSX devices, and (probably with some restrictions regarding system access and distiribution of the games) every game publisher will be able to publish games for the Touch platform very soon.
2. The touchscreen technology on the Touch platform is not comparable to the DS. Major disadvantage compared to Nintendo: you cannot use a stylus on Apple's device. Forget about pixel-precision pointing. Minor advantage: Apple's devices allow multitouch. You can give input with 2, 3, 4 fingers at the same time, which is not possible on the DS. So Apple Touch games will have to be quite different from DS games.
3. Someone said the games will be Java or Flash. No they won't, they will be native to OSX. Apple has ruled out Java software for the Touch platform because it's too slow (also deprecating Java development for their desktop OS), and if Flash support will ever come is up in the air. Really, these technologies are so 90s.
4. And finally on Mac games. According to the NPD charts of 2007, 7 out of the 10 bestselling Windows PC games were also available on Mac. Mac gaming is okay, though not great, and this has been debated elsewhere before.
Hardcore gaming is a bubble economy blown up by Microsoft's $7 $6 billion losses.
