This is already pretty much possible. A jailbroken iPhone gives you the best of both worlds - and you don't even need to go through the hassle of dual booting.

This is already pretty much possible. A jailbroken iPhone gives you the best of both worlds - and you don't even need to go through the hassle of dual booting. And it's actually ridiculously easy to get up and running. I would argue that a jailbroken iPhone is currently the best device available. You get Apple's slick UI and ease of use alongside Android's restriction-free environment. Interesting anecdote: I actually turned off multitasking with my jailbroken iPhone. Except for some very specific cases I think most people are going to find multitasking not a big deal at all.