The MBA was only updated a few weeks ago, so is unlikely to see any changes. Unless the rumoured 12" model appears, which seems unlikely so soon after the other models changed.
You are unlikely to see any negative issues from waiting. Potentially something new could appear that might turn out to be more appealing. It is worth waiting if you don't need it now.
As the other poster mentioned, it is unlikely. Might as well wait though, it is less than 6 days away. The only chance of one being announced is if an A-series notebook is released. Other than that, we will have to wait for an October launch.