blackhand1001
macrumors 68030
Quad Core CPU iPhone 5 is simply not going to happen. It'll take years for developers to even utilize dual core.
Single threaded performance is FAR more critical to application performance at this point. This is true even on the Desktop for many applications, and we've had quad cores for many years.
Quad Core iPhone 5S, yes, that is feasible in 2013.
More threads does make a difference even in apps that don't necessarily use all the threads.
The a5x is also a terrible soc as far as power consumption and I doubt it would ever end up in the iphone.