With Tidal Wave closed and the poor capacity of both Congo and Stanley, I think the park's first priority should be another water ride in the coming years. The only problem is attendance is ultimately more important than rounding out a ride collection. As far as water rides go, only super gimmicky, pilgrims plunge-like, rides seem to do for drawing in crowds.
With coasters, giving an RMC make-over to Gwazi would be amazing. But, as Mr. HTF said, BGT has already failed with a "new" Gwazi. I think you could even claim Gwazi permanently stained Floridian's view on woodies. Which is an absolute shame, Lightning Rod is probably the most amazing ride I've ever had the joy of experiencing.
Personally, I found Furry 325 to be disappointing outside the front row. The ride really ignores airtime besides the final three hills and being located in a field instead of near trees gives the back rows no real sensation of speed. However, I do think Busch would probably do a better job than Carowinds to place trees/themeing near the ride similar to how Cheetah Hunt's water runs counter to the ride track to exaggerate the speed. Seeing how Fury is somehow ranked 4th by golden ticket, if BGT and B&M got the ride right, they would have a claim to #1 steel and the advertising that comes with it.
And the biggest issue, especially for Busch and SeaWorld, is reliability. With Cheetah Hunt and Falcon's Fury being delayed plus RMC putting on a poor show with Lightning Rod, I'd be willing to bet a B&M giga could easily be in the future.