Instead of anointing Apple the "crusher" and "killer" of Pandora, we should consider where Apple might fit in and if, the bigger picture, the company's presence in the space will mean much. Will Apple be more like Spotify, Rdio, Pandora or a blend of all three? Will it work in other types of content, such as news and sports talk, like Slacker does? Or will it look Pandora in the eye and do straightforward personalized radio. I doubt it. I expect a Rdio-like service, though not as good. Say what you want about Apple, but it's never really been all that great at putting together awesome user experiences with software and services like it does, consistently, with hardware. That aside, it absolutely will fit in somewhere. It will, without a doubt, be a major player. But, just as it's imperative to draw distinctions between on-demand services, platforms that house your music collection (e.g., iTunes) and the personalized radio experience Pandora provides, you have to consider each service as one option in a sea of many viables (I love coming up with new words).
In the old days, we chose between radio stations on the basis of the style of music played or the personalities who talk between the songs and/or commercials. We no longer do that quite as often. Pretty much all Internet radio lets the user build his or her experience from the ground up.