Rides can stand on their own even if the IP is terrible. This is the same park that had Splash Mountain and currently has Tron. If the land is good (and it looks incredible) we'll be just fine even if the IP choice is weird.
As for what it replaced, as a Florida native Rivers of America was never special to me. It was just more of the nature that I grew up around. Beautiful, but not unique or special. This and Villains Land will finally give this park more rides and more walking space, something that it desperately needs.