That's interesting the noise tests came back with nothing... I wonder what would be considered problematic if not a ride with the word "scream" in the name lol.
ATVs riding through the Serengeti sounds like it'd actually be a cool concept if there was actually some effort to theme it. The biggest drawback I see is how obtrusive it'll be to the scenic/natural areas of the park, which are really the main thing still giving this park some charm, though sadly I don't think the park management really cares much about that sort of thing anymore.
The real question is, what could replace Sand Serpent? Removing that and Phoenix clears up enough space to hypothetically add a much-needed dark ride, and that's without even touching the HOS house or the kiddie rides.