As a fellow Air owner I feel exactly the same way. I like new toys but looking around between the macbooks and macbooks pro there's nothing I'd want to replace it with. To apple's credit the Air performs incredibly well and the only reason I looked into replacing it was because its 128gb SSD is a becoming a problem, so I'm using that as an excuse to upgrade into something newer and shiny but the only things I see that I'd want to replace it with are the surface book and the surface pro 4. I want to like the 12-inch macbook because of the form factor but I just don't want what in some ways is a noticeable downgrade.

If MS had that $650 discount on returning a macbook when buying their hardware in Europe, I'd have already jumped on it.