Wait? For what exactly? What are the benefits of the supposedly Air 3 over the Air 2. At this point the Air 2 is fit for iOS 9, with all the speculation of force touch being added to the upcoming models... We honestly don't know what value that would be.
Air 2 is faster, awesome display, has 2GB of Ram, already optimized for iOS 9 SplitView. I don't see a earth shattering update for the Air 2. Perhaps a iPad Pro would be a compelling reason to wait, but what will Apple add that will peak interest. With so many unknowns... What's the point in waiting. The Air 2 is a great product to own now... Mind you at a discount.
Longer battery life? Maybe higher resolution, I don't know. And Force Touch is very underrated. It has the potential to be very useful.
And yes, the Air 2 is great, I own one myself. I'm just saying one can save money by waiting.