How do you know they compromised by using the A5 chip? I'm betting it was intentional, as the A6 is in the iPhone 5, a device much smaller than the iPad mini. Everything else you said is also true of both the iPad and iPhone transitions to Retina, yet the price didn't increase there either. They even made the iPhone 4 thinner than the 3GS while simultaneously adding the Retina Display.
None of those reasons really support the argument that the mini will go up in price when Retina is added. I'm not saying it's impossible, but historically Apple hasn't done this and I don't see any compelling reasons why they would.
What is your source of information? Is this all your assumption, or do you have something specific telling you this? The Nexus7 is about the same size as the iPad mini, roughly the same weight, has a higher resolution screen, and is cheaper.
Either give us something substantial, or stop stating your opinion as if it were fact.