Since KECO folded in the early 1990s, and Paramount removed the Hanna-Barbera license in 2006, Hanna-Barbera hasn't been seen in theme parks ever since Camp Cartoon at Six Flags Great America was rethemed in 2018. What park do you think will own the rights to HB? I bet it'll be Six Flags, IF they ever decide to renew the license. Universal might still own the rights, but they've rarely done ANYTHING with it.
If AT&T buys Six Flags (which I really, REALLY want to happen!), they'll own the rights to HB. That means they can bring back the Enchanted Voyage with newer characters like the Phantom Virus, and use the action characters like Space Ghost and Birdman in more intense rides (I want a Birdman themed flying coaster!)
Or maybe today's kids just don't care about Hanna-Barbera, because Boomerang has become a ****show and rarely airs classic cartoons. Aside from Scooby Doo, Hanna-Barbera is literally an outsider in these kids' eyes. Mention Fred Flintstone and they'll be like "Who?" (Then there's the "GRAND DAD" meme, but that's a different story.)