Why not? Two distinct lines:
MacBook 12": Thin, light.
MacBook Pro 14": Powerful, thin, light.
Legacy:
MacBook 11" for education (Low cost).
MacBook 13".
rMBP 13".
rMBP 15" gone, and replaced by MBP 14".
Good good good good good... good. good. good good.
Supply slowdown means that they're finally ramping down production for the 2014 (technically 2013) rMBPs, with something new inbound.
Hopefully it'll launch at WWDC, instead of Q3/Q4/2016 Q1. WWDC launch/announcement makes sense, because it'll coincide with OS X 10.11's release, and not clash with the iPad Air 3/iPad Pro and the iPhone 6S announcements during Q3/Q4.
I really think this idea is going to come into effect at WWDC. My concern is that the 14-inch will drop the dGPU for good instead opting for the Iris Pro iGPU. Only 2 months from now.
12-inch will replace the Air and the 14-inch will replace the Pro(s). Bigger screen in the form factor of a 13 inch with better integrated graphics (maybe only dual core though, who knows - trying to tamper my imagination, but I think Iris Pro is restricted to quad core? I don't know!).