If you mean if a developer in MSFS can create a GSX integration like the one made by FSLabs in P3D, it's surely possible, the number of available LVars available to developers to interact with GSX has even increased.
Leonardo's MD80 have some good GSX integration and, you might want to check the Fenix2Gsx free add-on, to integrate the Fenix A320 with GSX Pro.
