Paula dropped the first hint:
"Promised to start leaking a few details about 2011 today. For next year in Holiday World, we will replace one ride with a vaguely similar ride."
They could possibly replace "Paul Revere's Midnight Ride."
Another guess I read: replacing the canoes with a splash battle.
Some discussion is already taking place in this thread:
http://coasterbuzz.com/Forums/Thread/57932.aspx
Holiday World stated on Facebook that it will most likely be something in Holidog's Funtown.
Closed topic.