A5X die shrunk, is smaller than A6X, means many things.
But we have not actually heard that the A5X has been die shrunk, it's too early to make that assumption.
The article merely states when the original A5 was die shrunk, no confirmation of the same thing for the A5X. At the moment all they have is speculation which is as about as accurate as anyone guess here.
It's also likely they were just using up A5X chips that were manufactured for the iPad 3 before it's untimely demise.
Remember the AppleTV is still relatively niche so a decent stock pile of A5X's would fit nicely into that bracket as it looks unlikely that the new Apple TV will be bringing with it any new GUI or changes in regards to Apps. It's designated 3,2 (as opposed to 4,1) for a reason.
Likewise...
It's too early to predict and A5X in an iPad mini, especially if the iPad 5 goes to the A7, which would put Apple's now most popular iPad two generations behind it's bigger brother in cpu. The is just as much chance that if the A7 is going to be used in the iPhone 5S, iPad 5 then it too will just as likely be used in the iPad mini.
The A7 we should assume will be more power efficient allowing the iPad 5 to be made smaller and thinner, and without causing the iPad mini to gain weight or lose battery life dramatically because of the increased performance.
But again this is just speculation and has about as much merit as the speculation in the front page article. Only time will tell.
I'd advise against banking on this.
Maybe, maybe not.
But quadcore isn't a benefit in mobile devices. From the wide range of photo, movie editing apps, and the likes of Infinity Blade 3 etc. The user experience with dual core is top notch.
Spec sheet whoring is the only reason for quad core. Further evolving dual core architecture for performance and battery efficiency is still a better route for this and next gen.
A8 or 9. A hair bigger maybe.
Maybe so. But we can at least assume the GPU will be more advanced, and therefore it may not need that 'X' variation to drive a retina display. That is more the important factor I was taking into consideration in regards to the a7.