In my opinion, it would depend on the quality of the water park.

I just got back from the Atlantis Casino & Resort - right on the Caribbean ocean. Most of the people there had children who were there for the water park. I went to swim on the beach and there were not that many people there. I think the new Revel owners are on to something - attract the kids and the parents will follow (especially with the casinos). An issue would be the winters, but I think AC has always had to deal with that....