I think the park certainly needs something for people who won't go on roller coasters or flat rides. There's not much to do for the "stay and watch the stuff" kind-of guests. I think something like a boat ride could be a good fit since they got rid of Tidal Wave. Rhino Rally would be a good location for that since all the other water attractions are located in the back/left side of the park. I also think a boat ride would be less likely to cut into the park's safari sales, because that is probably a very lucrative part of the park.
Right now, the park's strategy seems to be, how can we put the most buzz words on a billboard to advertise the rides. This can be seen ever since Mako "Tallest,Fastest, Longest" same with Tigris "Florida's First Triple Launch" and now with Iron Gwazi" "Fastest, Steepest ect. " Considering we haven't really seen the chain add anything that hasn't used this marketing strategy, I doubt they'd be interested, but I think overall guest satisfaction is higher when you have attractions for all to enjoy. And with Iron Gwazi, the park can go several years without any new coasters.
I really think it would be a disservice to the park to put a large flat/coaster in the rhino rally space. A nice, themed, lush boat ride would be perfect for the area. The park needs something else. Less Six Flags please.