The benefit is easy to see. It could bring them additional market share.
No, it would be bring additional shares, because they would not be selling a binding, just a plate. If Salomon was interested in "market share" all of their bindings would be branded as Salomon bindings, not Salomon, Atomic, Armada and even Stockli which divides their shares. IMHO, they should, I think it would be clearer to the consumer, that is one of the reasons Look brought all the brands back under one label.
If I can use my Salomon Bindung on two or more different skis, I am likely to buy Salomon in the forst place and not Marker or something else.
You can. Why would you not buy another Salomon over say a Marker or something else? You cannot buy addition plates for their bindings either. But also with any system binding such as these , you are costing yourself a bit of performance.