Correct me if I'm wrong but didn't the mac book pro retina 15" version go from 45W to 47W.
47 TDP is the max the chip will operate at so if and I struggle to believe apple can't shoehorn it in they can drop or undervolt the chip.
In short there are various ways round it but I don't believe the design of the mini is what will keep the iris pro out of a refresh, price will be.
First, I am not sure whether or not 15'' rMBP supports MAX TDP 45W or 47W or more...possibly it supports enough Watts to host Iris Pro 5200.
Second, APPLE might delay new Mac Mini update because they try to redesign the external case / re-arrange internally the components to host Iris Pro 5200 graphics + quad-core i7 along with TB2 (and USB3.1?). That means we have to wait till Apr-May 2014 to see a fresh Mac Mini. I don't support this approach but I think it is likely to happen...