With SU10, there will be a new API in the SDK we can call to get the data we need about an airport, without having to open its .BGL file directly, and this will solve the problem of Marketplace airports.
The API is still in Beta, we are already working on integrating it with GSX, is still not complete ( it miss data about jetways, jetway links and runway starts ), so there's no telling exactly when it will be usable by GSX, but you can be sure we'll use it as soon is ready to use and has all the data we need.