Apple has reached a young audience that PC's never will.
Well... considering that up to today PC controlled 99% of the market... and that young audience is at least 60% of that (excluding companies) I would say they did reach to everyone they wanted. They still control the market, and they still have a lot to do with Apple. Especially now that Apple will have Intel processors, it will basically be same as a PC with a different software.
What Apple did, is that it made the transition to the Digital Era much easier to everyone... I have been involved in it, MP3s, digital video and music for years... and nothing made the switch like the iPod and iTunes did... thats the most impressive thing I believe... and the way they managed to stay ahead in this game which is very hard... the iPod will definitely be Apple's #1 accomplishment ever... and it has nothing to do with PCs