There is already only a $100 price difference between the i7 Air and the base rMBP (whose full voltage processor has similar performance). It's possible that Apple will leave a non-Retina "budget" option for a time. It's also possible that, like today, they will use a lesser quality display (lower color gamut and/or contrast) to improve yields and keep the price differential.
Agreed. They would have to do something to distinguish the Air and rMBP lines.