FYI, that's actually an early mockup of the iPhone 6 from an article a few months ago.
I will probably use my 6+ and iPad air just about equally. My MBA doesnt get used much at all.
I also cannot imagine having an iPhone, iPad and an Apple Computer.
I've tried owning an iPad twice, and both times, I've just found the iPad and Macbook Pro to be too redundant.
The iPad really seems to be for someone that doesn't have an Apple Computer, or has a particular need for it (i.e. ebooks).
If anything, it seems as if the larger iPhones will cannibalize iPad sales.
Depends on how you use your devices. I own a Mac Pro, a MacBook Air, an iPad Air and an iPhone 6. I use all of them. None gets neglected.