In my mind, makes perfect sense - the President of Hockey Ops becomes the "face" of the hockey franchise - he's responsible for the overall direction the hockey team takes. Makes sense to make it a hockey player.
Leiweke then gets out of the public eye around changes with this team and can concentrate on being "behind the scenes" rather than in front of the camera (notice, everyone is talking about Leiweke now rather than Nonis to make changes).
With the new Pres of Hockey ops - he gets to evaluate Nonis, Carlyle, Scouting Staff and all of them and if it doesn't work, bring in someone who does know.
Almost see this role similar to what Linden got in Vancouver, or Phil Jackson with the New York Knicks.