They've been hiring Android developers recently to work on the Beats music app, which is likely to become the Apple streaming service, so there's a good chance it'll be on Android too. No idea whether it'll be any good, of course.

I suspect the main thing that will limit Apple's streaming service is availability: iTunes Radio is only available in the US and Australia. I think they're being punished a bit by the record labels, after Apple took over the digital downloads market, much to their displeasure.

That said, if Apple's streaming service comes to the UK, I know I'll drop Spotify in a heartbeat. I couldn't be more disloyal to Spotify: I only use them because they're the only service with the exact combination of features I need (besides Rdio, who I don't use because their desktop app is - incredibly - even worse than Spotify's).

Their words, not mine. And Apple doesn't have to kill Spotify: it's important to remember though that Spotify exists basically at the pleasure of the music industry at this point. By all accounts they aren't contributing a lot to the bottom line, and I have always gotten the sense that record execs are just viscerally uneasy with Spotify's freemium model--they want to move towards a world where people become (re-)accustomed to paying more, not less, for music. How this all shakes out with Apple is anyone's guess but if there is one value which Apple certainly does not espouse, it's "free". I think record execs are way happier to be in bed with that sort of company in the long term.