Essentially, we have a bunch of rumors. Plus a bunch of speculation. Plus some arguments what would be a _reasonable_ product for Apple to offer. Of course it is the combination of product and price that matters.
If they wanted to kick Samsung where it hurts, they should offer a cheap and cheerful 5.2" phone. To establish that huge phones are for people who have neither taste nor style nor money to afford a real iPhone.
The iPhone 4 has a single core CPU. Apple's still selling that. A single core A5 would be a performance upgrade over the single core A4 of the iPhone 4 that it would replace in the lineup.
How long have you followed Apple? They aren't concerned about how the specs stack up on paper. They care about how the device works in the real world. A single core A5 would work just fine. Considering that they have such a chip in the Apple TV, they clearly have bigger plans for it.