New Media like iTunes is on the web, however they still charge people to buy songs and music videos, etc. This is the old media way of doing business. The new new media way of doing business is by making everything as free as possible. If you want to listen and/or watch Bruce Springsteen's song "Born To Run," why pay $1.29 on iTunes to buy the song, when you can listen to it for free on YouTube? Free is better, and that is one big advantage new new media has over new media on the web.
However, iTunes does have it's advantages. First off once you buy the song you may access from your computer with iTunes, or practically any other medium that has the letter "i" in front of it (i.e. iPod, iPad, iPhone, etc.). Secondly, you do not have to worry about any copyright problems that YouTube has had in the past with people posting videos or recordings online. Thirdly, the library of music available on iTunes is greater than that of YouTube's and because iTunes is dedicated to music and other media it sells, it is much more organized than YouTube is.
In short, even though free is better, iTunes will still endure despite YouTube. iTunes may struggle a bit because of YouTube, but YouTube will not be the sole cause of death for iTunes.