Seriously, this is the most "corporate U.S.A" idea I ever heard. I love it.
I think the idea makes sense, because if they are considering tearing down a practically brand new ride, they are going to do it based on a sure-fire heavy hitter to displace the money lost on what would essentially be two projects. Another potter based attraction makes sense to gamble on replacing an obvious dud, and with a refreshing of the area, they invite the prospects of new F&M opportunities, etc, combined with the draw of "potter". Lightning will continue to strike, and people who have visited UO just for Potter will return for more. It also gives them the opportunity to exploit another popular international franchise simultaneously by fixing a serious error in judgement, and now they also have the data in place to see what type of experience consumers expect for that experience. They can knock it out the park, and they can begin revitalization of a neglected area of the park, even if it means closing one of their more popular attractions.
Not to mention, GP already refers to WWOHP and UO as a whole as "Harry Potter World". Though, I think for sure, after this addition, US has more than enough potter... With one caveat. If they have the balls, get rid of FFL too and do that ministry of magic thing back there. If they fear needing a large theater, earmark the animal actors stage for a revamp. That needs a new show, and Kidzone needs something to bring them up to the level of park operations, park standing and pedigree they are courting.