I’ve been thinking about this for a long time, but with recent rumours about the Air not getting a retina update I think it’s increasingly likely.
With the iPad mini undercutting the full size iPads sales as a content consumption device, Apple are likely to push the iPad’s content creation abilities. This consequently puts it in direct competition with not only Windows 8 machines but also Apple’s own MacBook Air.
This is not a bad thing for Apple though. It’s iOS division is its money maker and iPads are Apple’s biggest growth market with high margins for profit.
The MacBook Air will continue to exist for a while but with incremental updates until it goes the way of the white MacBook.
A non retina MacBook air maybe a sign of this upcoming change, but if Apple release a keyboard cover for the iPad than its a certainty.