I made a separate thread about this and it “seems” that they will. Lone Rider said the racks will mean that anyone with the BMW motobags will be able to move them over to the 1300 with “no adjustment” and looking at the shape of them it seems they’ve made them to match the 1200/1250 ones which would make sense if they are saying the motobags will move straight over.
So if that’s true I don’t see any reason why the original OEM hard panniers wouldn’t fit as well as say the Bumot ones designed for the BMW racks. In theory anyway