The current gossip on Screamscape says that Boomerang will be the next ride to be removed (Finally!!!). If this happens what would do you think (Or would like to see) replace that? Boomerang and the former Riptide space makes for a descent plot of land.
I really hope that they will use that space to build a practical dark ride by Garner to make up for the Iron Reef letdown. If Six Flags can build a new building for a dark ride, Knott's should. Realistically though, I see another coaster occupying that space. It would be a real shame to have some prime land open for a descent dark ride only to have another steel monster occupy it.
I'm gonna be really, really, really, REALLY disappointed in Knott's if they use that space for another family coaster. If they opt for a coaster over a dark ride, at least make it thrilling.
I would love to see a new time travel-style dark ride. With a budget, they can have a handful of dino AAs and descent sets. It'd be easy to market and it would be a hit.
EDIT TO ADD: You know, if they REALLY wanted to be creative with the space, the dark ride wouldn't need to be so big. They can have one and put a family-ish coaster that goes around the Boardwalk. Something compact, flexible around the area, and something family friendly-ish and slightly thrilling. Intamin Megalite, anyone?