It's a recurring pattern that Apple has to re-invent the entry level laptops every once in a while because they've become so powerful and versatile the target audience for the "pro" laptops starts to prefer them over the heavier, more expensive and overly powerful high-end alternatives.

Personally I have found myself continuously switching between the "pro" and "regular" offerings ever since the days of Powerbook and iBook, and if a 12" Air would be nothing more than a newer, better Air with a retina screen I would probably pick it over the 13" Pro I currently use.

Apple regularly moves the goalposts to avoid cannibalizing the high-end line.