I'm normally in the "Apple would never create a convertible device" camp, because they are normally against convergence of devices unless there's a singular purpose. But then again, I'm also the person that all but insisted that Apple wouldn't make a bigger iPhone that can't be used with one hand. I was wrong on that. Kinda.
The iPhone 6 Plus is bloody huge, but when moving from mine to my wife's phone, the iPhone 6 suddenly feels like "the perfect size". I don't know how they did it (thinner body, rounded edges, narrower bezels, etc) but it truly works.
That being said, I think they may be a reason for thinnest and maybe this is a converged product in the sense that it has two parts. Let me explain.
What if the screen *was* the iPad Pro? Retina widescreen with a battery AND an A8X, Graphics processor, or what not. Completely standalone and runs iOS.
BUT... make a keyboard for it that contains an Intel chip, storage and RAM with real keys and another battery. Now you have two products. Rip the screen off the cleverly designed Jony Ive hinge and you got an iPad with iOS and 14 hours of battery life. Pop it on the keyboard and you got full-blown OSX. The trick is...
Continuity.
So while most of us are using that with our normal laptops and iPhones, this thing will use it internally to transfer the work between iOS and OSX.
Now the other really cool part is that this keyboard device can also be used as a Mac Mini replacement. Now you'd have a great keyboard and trackpad hooked to a full computer. Just plug in a monitor or use AirPlay to use on an HDTV, etc...
Anyway, I digress. It would really need a lot of care and attention to detail. But if any company could pull it off (and has nearly all the pieces in place), Apple can.