Rumors says that Apple will upgrade the MacBook Air to have a Retina display in Q3 this year. But the rumor just say that "Apple will do a facelift of some external features", so that could also mean that it will get a touchscreen as I have been talking about in videos. Personally I would prefer a touch sensitive screen over Retina.
There is some problems with adding a Retina to the MacBook Air. One problem is that the screen will need to be thicker than it is now, so Apple must do a complete re-design of it.
Another problem is that it would be more expensive. It will cost as much as the entry level MacBook Pro. Maybe Apple will release two versions as with the MacBook Pros, one with Retina and one without. Here is more why it will be hard to add a Retina display to the MacBook Air.
I think the next step for OS X and the MacBook Air is a touchbased UI and screen.
That would be awesome. At least on my favorite 11-inch model. I can already now hold and use it like an iPad. With a touch sensitive screen it will be even more useful. No need to move the hands down to the touchpad when holding it in the screen for example.
And I don't want a detachable keyboard. There is no point in that. We don't need another Surface Pro. The keyboard is not in the way at all. In fact, it makes it even more confortable to hold than the iPad, because you can put it on your knee or stomach while reading or watching movies. No need to hold it.
The MacBook Air could be the next revolution for Apple if they do this right.
Update: KGI Securities analyst Ming-Chi Kuo suggests that Apple will introduce new models of all MacBook's at the WWDC 2013 10th of June. They will have Haswell processors, that is expected to give much better battery life. He also says that we will not see a Retina display version of the MacBook Air, because Apple cannot make a Retina version at the MacBook Pro’s price point and size, and I totally agree with this.