As I said in the Bowie thread, expect this to be an accelerating trend. All the old rockers are getting up into their late 60s at least, and as Kerouac pointed out, most of these guys lived pretty hard and fast for much of their lives.
You also have to keep in mind that these guys don't seem like they should be this old. We tend to remember them from the glory years, and they all have excellent hair stylists and plastic surgeons to keep up the illusion. That makes it much more of a shock when they pass.