I doubt a Macbook Air with Retina, too (in the near future)
Don't they already have 13" Air Retinas...13" rMBP? It's not like Apple didn't try to design the 13" rMBP to be as thin as possible.
I just do not see such a move, given the lack of history of Apple moving that quickly to a substantial redesign of its laptop nor desktop lines (i.e., two substantial changes requiring body/housing changes in two years). Given the needs of Retina including the power draw, I would guess Apple and suppliers are at where they are (with a reasonably battery life) with the current Macbook Pro 13" with Retina for at least two (probably more) years. Most reviews I read were not complaining about the size/weight of the machine (in comparison with the Air, which granted is still a significantly lighter design--though significant and critically important may not be the same things for the majority of people in this case ). Most people complained about a) the cost (Apple fixed this one recently. Hopefully, the current pricing stays in affect for Haswell); b) the lack of a quad core cpu (standard or optional). It seems like it at least will be feasible option with Haswell given the power reduction that Intel seems to have been successfully focusing on, rather than massive overall cpu performance increases; c) discreet graphics vs the integrated Intel solution of the day. I looked hard at the internals of the current 13" Retina body, and I see no hope for game/graphics enthusiasts there. Let's hope the GTx/HD5xxx is really as big a leap as Intel is leaking (though, for many people, the HD4000 seems to be OK, so Apple probably made the correct choice by not making the chassis any bigger nor degrading the run time any more by including an AMD or Nvidia card).
I would bet two cents that what we will see (as many people have already said) is a complete removal of the non-Retina Macbook Pro line combined with a positioning of the Macbook Air as the entry and probably majority line (for the next year or two when Retina displays still command a hefty premium). Probably bump the standard $999 11" config to 128GB SDD, add in Haswell, and call it a day. I would love them to knock a $100-200 off the base prices (would definitely help their market share), but I would not bet my precious two cents on that. As nice as Retina is (and it is, and not just because of the resolution), a 13" Macbook Air with 4gb of ram, 128GB, and Haswell at $999 is probably damn near a perfect machine for high school and college students, sys admins (if 11" is too small for comfort), and most managers and non-engineers in many corporate environments.