Sorry but Indianapolis does NOT need a theme park. Reason is actually simple..that city is just a bit too close from, well everything. Didn't Indianapolis a few years back spent a ton of money in launching NON-STOP bus service to Chicago some years back called the mega bus?
also in this day and age of lawyers and such, if anyone in Indy would dare to try to open up a theme park in that city ( no matter how big the city of Indy gets )..chances are one would hear from the lawyers from either Holiday World or Indiana Beach. Chances are..well it won't be nice. Be kinda like the city of Balitmore asking for a theme park and dealing with Six Flags lawyer's over Six Flags America...its called "not on my turf you won't..now back off".
...and this is coming from a guy who IS from Indianapolis.