I doubt we'll see those for AAMs. Technically it could easily be done, but fact is that Flanker is a platform with so many hardpoints as it is, that often time it doesn't even have to carry the max number of missiles in a mission. Unless the air combat doctrine really changes into mass missile spam (So far, despite F-15x being shown with a bunch of missiles ,that doesn't seem to be the case) i doubt we'll get those twin racks.