Just a wild guess of mine.
Since the air is likely to get the retina facelift (hopefully this year- killing off the mba 11" which is essentially the macbook retina size wise, probably killing the current mba's & cmbp 13") & speculation about the ipad pro 11.7" or so...
This would could then nicely fill the inch gaps throughout the product line ; 11" (ipad pro), 12" (mbr), 13" (mbpr), 14" (mbar), 15" (mbpr)
we shall see...., just my 2 cents
Since the air is likely to get the retina facelift (hopefully this year- killing off the mba 11" which is essentially the macbook retina size wise, probably killing the current mba's & cmbp 13") & speculation about the ipad pro 11.7" or so...
This would could then nicely fill the inch gaps throughout the product line ; 11" (ipad pro), 12" (mbr), 13" (mbpr), 14" (mbar), 15" (mbpr)
we shall see...., just my 2 cents