I doubt a 13" Retina MacBook Pro
I have read alot of speculation lately on the 13" MacBook Pro retina lately and so here are a few facts that we can derive from Apples latest behavior.
1. Apple is set on making every last product "retina" quality.
2. Apple holds onto designs and products for at least a few generations.
3. A MacBook Pro retina 13" will not have an optical drive and will be based around flash storage.
Based on these three ideas that I don' t think that anyone would dispute imagine a future lineup where there is a MBP 13" retina and a MacBook Air 13" retina. they would be very close to the same machine despite some slight hardware advantage given to the pro for being slightly bigger. Therefore, I think that in the near future when Intel integrated graphics prove powerful enough to handle it the Apple MacBook lineup is going to look like MacBook Air 11", MacBook Air 13" and MacBook Pro 15". All sporting retina displays, the first two for portability and the last for power users.