My speculation....
1. This new 12" retina MacBook, closer to the size of the current 11" MBA, with a skinnier bezel and a new design language. (I'm guessing this screen will also be used in the alleged iPad Pro.) I bet this will push the boundaries of what ports a consumer laptop has...SD card? maybe not. Lightning instead of Magsafe/Thunderbolt? Only 1 USB? What about a second Lightning rather than audio out/in? The product seems queued up for late 2014/early 2015. I bet it'll initially live next to the current MBA lineup, until.....
2. A similarly styled 14" retina Macbook, more "Pro", probably not discreet graphics but Thunderbolt so it'd be a bit thicker than the 12" above. Size wize it'll be close to the 13" MBP and MBA, replacing them both but thin like the 12". At this time Apple will end the 11" MBA and hang on to the 13" MBA as the value machine. Let's guess mid 2015 on this guy, WWDC time frame.
3. Released at the same time, a 16" retina Macbook, replaces the 15" in size and yet gives the 83 or so people out there clamoring for the return of the 17" something to praise. This one would be the most Pro...but still thin and light. Again, WWDC time frame.
So by middle of 2015, all current MBA's & MBP's are obsoleted, replaced by this new thin and sexy Macbook something, all retina, 12", 14" & 16". All Intel inside regardless of how tempting an A8 based machine might sound.