Upon looking at my MacBook Pro's 15.4" display and using the laptop, it becomes abundantly clear that an iPad of that size could be possible and comfortably usable with the caveat that Apple put it into a form factor that's under a pound. Now, this may rely on battery technology and power efficiency improving more than anything but if Apple could build a 15.4" iPad as thin (and light 
) as the rMBP display. Frankly even at roughly 1.5 pounds I could see the iPad Pro being uncomfortable to hold up for longer than a few minutes, but in my opinion the weight matters more than the physical size in regards to long-term usability.
) as the rMBP display. Frankly even at roughly 1.5 pounds I could see the iPad Pro being uncomfortable to hold up for longer than a few minutes, but in my opinion the weight matters more than the physical size in regards to long-term usability.