Do you guys think we're likely to see Apple release a Retina and non-Retina MacBook Air ?
Personally, I think Apple will move to fully eliminate non-Retina machines (perhaps by 2015), as to take advantage of economies of scale; but perhaps the price 'jump' (if any) would price the Macbook Air out of the 'market'.
I'm highly anticipating a redesign as well.
I don't think so.
I think Apple will discontinue the current non-retina MacBook Air and release a brand-new retina MacBook Air to replace it. Of course I can be wrong, but I think the scenario here is completely different from the one in 2012, when Apple released the retina MacBook Pro. And here's why.
When Apple released the retina MacBook Pro, it was a very expensive machine because of
the retina display itself, which was more expensive than regular displays; and
the SSD storage, which was much more expensive than regular HDs.
For this reason, Apple kept the non-retina MacBook Pro at its regular price and introduced an overpriced retina MacBook Pro. In 2013, Apple reduced the prices of the retina MacBook Pros and discontinued the regular models (except for the lower-end 13-inch). Now, it's different, as the two elements that boosted the price of the Pros are not present here. Let me explain why I think so:
The retina display is not as expensive as it was in June 2012, when the retina Pro was released. In June 2012, ultra-high resolution displays were new and, therefore, very expensive. Now, they're becoming cheaper and cheaper. In addition, the rumored resolution of the new Air (2304x1440) is not the quadruple of the current Airs, as it happened to be with the Pros. So, the price increase will not be so great due to (i) a jump not-so-high in screen resolution and (ii) the popularization of high-resolution displays, which are cheaper now than in June 2012 (and will be even cheaper in mid-2014, when the retina Air is likely to become available).
Flash memory is still very expensive, but the Air already got it. When Apple released the Pro, it replaced the HDDs for SSDs, which resulted in an increase in the price. But the Air already has SSDs inside, so there's no price jump here.
Due to these reasons, I think Apple will discontinue the current Air (and perhaps even the entry-level non-retina Pro) and release a brand-new retina Air.