You can safely assume the library of objects available in GSX can only improve.
We had more vehicle variety in the P3D version, but we didn't want to recycle old objects in MSFS, at least not those that even there weren't already made with full PBR.
So yes, everything will be expanded, but priority will be given to new vehicles that will allow new functions, like the new Fuelers that will serve airplanes with lower wings, which right now don't have any animation.