That just seems odd to me. I know there were crossovers in animated specials and movies, but doing it with a live action line up seems... Well, just odd. And aside from a few of their properties, how many still have strong recognition with children and even young adults today? Scooby Doo, The Flintstones, The Jetsons... Maybe Yogi (though we saw how meh the live action Yogi film played out compared to a the budget and advertising costs.) I hope I'm wrong, as I'm a big Scooby fan (though I could take or leave most of their other properties.)
Anyways, as far as the rights go I'm not sure. I wouldn't be opposed to seeing a Scooby attraction, and Universal Hollywood still has some remains of the Flintstones area if I'm not mistaken (which I totally could be)