You're actually, very very right!... It's a mistake to talk about a 12" rMBA. Nobody's giving that kind of description on Apple's side...
1) Apple may be considering to kill the "Air" line (with the non-retina display) by the end of 2015 (or early 2016....).
2) In 2016 we'll surely see the 12" rMB with Haswell and I prophesize there will be a bigger mate with 14" rMB.
3) If above comes out true, the 2016 rMBP line may have a 15" model and a re-incarnated 17" rMB model with Skylake; but the 13" rMBP may be dropped off to give way to that 14" rMB.