I think the problem is that this is really hard to do. All-in-one devices more often than not don't do anything well, because they are trying to do everything.

This is one of the reasons Windows 8 is so confusing. It's your good old windows experience. No wait, it's a brand new tablet interface. You can install Metro apps... but you can also install existing apps...as long as they never interact. It's meant to be used with a touchscreen....but also with your keyboard and mouse. It does everything, but nothing well.

I'm not saying you couldn't have a phone that doubles as a laptop, that doubles as a desktop, that doubles as a video game device. But I think it's really hard to make it coherent.