Anything is possible - however my guess is that if the MBA is indeed getting a whole new form factor and brand new design, that it will get its own event, and not be a part of WWDC. If the MBA is just an iterative update, and retina + Broadwell are the only "big" deals, then it may very well get announced at WWDC...certainly hope we get something "revolutionary" that will bring ultra-light computing to another level...again
I am not so sure of that. In 2012, Apple released the retina MacBook Pro during WWDC, and it was something. I do not think Apple will hold a Mac-only event anytime soon. The last Mac-only event was in October 2010, when Apple released the redesigned MacBook Air, and it has been more than three years. I do not think this time Apple will do another Mac-only even, although I may be wrong.
I do not think the MacBook Air update will be only the introduction of a retina display and Broadwell. If the current Airs go retina, then the screens would be an 11-inch 2732x1536 and a 13-inch 2880x1800. That is not consistent with the current retina MacBook Pro line and also not consistent with the rumors that come from the supply chain (and which point to a 12-inch 2304x1440 display, with roughly the same pixel density of the 13-inch retina MacBook Pro).
So, it is very likely that the MacBook Air gets a redesign this time. This is not only consistent with the rumors of a 12-inch retina screen in the production line, but it is also time for an update. The MacBook Air was last redesigned in 2010, and Apple is being consistent in redesigning its lines of laptops once every 3-4 years. Apple will not lose this chance to redesign the Air.
Now, I do not think something truly extraordinary is coming. I have seen the rumors, and I have read what Kuo expects. Everybody praises Kuo for its track record, but he is certainly not infallible. He has been wrong before, and I guess he was more times wrong than right. He expects the next MacBook Air to "redefine laptop computing once again". I do not.
I do not see what a new MacBook Air may bring that is not already in the market. The first MacBook Air, in 2008, was really outstanding, a piece of design and creativity, that shaped the future for mobile computing. Of course it was expensive and not very practical, but, still, almost a work of art. The second-generation MacBook Air, released in 2010, was quite similar, but much more practical and also cheaper. While the first Air shaped the future, the redesigned model brought the future to the present, allowing people to actually have it as their laptop. It was revolutionary in this sense. All this ultrabook market came after the Air, and now there are thin-and-light laptops that fit all tastes.
Now, what is left for the next Air? Being even thinner and lighter? We already have some ultrabooks which are thinner and lighter than the Air. Retina display? We already have ultrabooks capable of a 3200x1800 resolution, higher than any Apple product. New materials? We already have carbon-fiber ultrabooks. Battery life? Perhaps, but the current Air already reach 12 hours of battery life, and I have read some users that beat 15 hours in one charge using OS X Mavericks. So, what can the next Air bring to be so revolutionary? I am curious. Perhaps Apple puts everything in one package, make it thinner, lighter, put a retina display on it, a better battery life, and add a fanless design and LTE connection. Even though, would it be revolutionary, as almost all these features are already available in other products?