No -- it could, but you'd have to do some machine work on the slide.
Well wait, haha, let's clarify. If you are talking 95% of all the fixed rear sight 5906's ever made then you are speaking of the famous Novak Lo-Mount sight. And no, the 915 slide would need some small machine work to accommodate that legendary sight.
However, the very earliest 5906 pistols with the fixed rear sight work a simple fixed blade just like the fixed sight 639/659 pistols, and that dovetail is probably the same as a 915.