On their Facebook page, ImagineSim has announced they have released an update for their Austin (KAUS) rendition. This update just reconfigures the airport for Prepar3D v5, there are no new features yet. New features that are possible with v5, like sloped runways, new light effects and more sophisticated terrain and mesh will come at a later date. The team is still working out how those new features work and how to implement them.
You can install the update from the Operations Center. They do say that the v5 version is only available via the Operations Center. People who want to buy the airport need to buy the v4 version from their website and update the products via the Operations Center. You can buy KAUS here for £22.99.