I don't think it will be a simulator, purely because running a ride like that requires lots of staff... and that is something that Village really doesn't like spending money on. As far as timelines go, I'd say they will keep Doomsday till 2026 which is when it comes up to its 10 year strip down. If they decide to keep it after that, they are honestly incredibly stupid.
As much as a Gyro Swing would be a good fit (size wise) for the area, I really hope they don't go down that route however another flat ride is really needed purely for the capacity and for something that isn't a roller coaster. I don't think Wild West Fall's days are numbered just yet as someone mentioned, but maybe when it's time for the next 10 year rebuild they may decide to go with something new in that space. Really, I think what Movie World needs to round out the park is another 2-3 flat rides, a decent family high capacity ride (Potentially a replacement for JL in 5-10 years), an overhaul of the kids rides and another thrill coaster to replace Green Lantern when the time comes. For coasters they have most of the categories filled (Thrill: DC Rivals, Superman, Green Lantern and Flash. Family: Scooby, Wizard of Oz coasters, Kids: Road Runner).