You seem fixated on watching Youtube videos...
Youtube is not the end all and be all of what many(I'd say most) of us do on our computers. My iPhone 4s loads Youtube videos faster than my G5. It's not replacing my G5 any time soon-there's a whole lot my of stuff my G5 can do better and faster than my iPhone.
If I want to watch Youtube videos, I use an Intel Mac, or my iPad, or my iPhone and not a PPC mac. As I said, though, that's not all I do on my computer-in fact it's about 1% of what I do on my computers.