From the description, it doesn't seem different at all to what we already have in all our sceneries, we use it for regular airport ground traffic but also for other things including the kite surfers at the hawaiian airports, they are not canned gmax animations, but multiple independents paths that are followed by vehicles with their own physics simulation. We have it on any airport starting with Zurich, which was released 4 years ago.
It's such a trivial feature that, compared to how advanced GSX is, that we never really advertised it with so much emphasis, it's just convenient since it's not a keyframe animation, so the path can be of any length and it's very quick to do comparing to a gmax animation.
To reply to the original question, any airport in FSX will be supported by GSX automatically. Of course, the airport should have features that makes *sense* for using FSX on it. Big pushback trucks or large passenger stairs will not be very useful on a bush airport.