I've been waiting for this. I always love trying to guess what our additions will be like next year. It is a very tricky thing to master, especially since Six Flags has thrown some curveballs (like the Tourbillons that GAdv and OT are receiving next season). I think Neal Thurman and Six Flags are trying to eliminate the Old Country "emptyness" and this is shown through the 2017 and 2018 investments being placed back there. I think in the upcoming years, they will try to finish off that section of the park.
Here is my 2 year prediction:
2019: With a family ride added in 2017 and a thrill ride added in 2018, I think they will try to please both the thrill seeking guests and the guests looking for tamer rides. This could be with the addition of a Giant Discovery in the old Autobahn area. It could use the Wonder Woman Lasso of Truth name. For the tamer part, they could give a DC Super Friends re-theme to some of the kiddie areas. I also think that they will start deconstruction on the Batman Stunt Arena during the 2019 season to prepare for their 2020 plans.
2020: It will be 4 years since they added a coaster in the 2020 season. Keeping with the idea of reviving the Old Country part of the park, I think that Great Adventure will add an RMC Trex Coaster (Maybe using the Lex Luthor theme- Lex Luthor's Fearless Flight). This could be possible, because RMC stated that they want to test out their Raptor Coasters before moving on to their Trex products (I don't know exactly where they said this). This could be placed in the area that Batman Stunt show stood and would take up some of the surrounding area. This would also make many of us enthusiasts SO happy! (And hopefully the GP would go crazy for it).
Please let me know what you guys think of my predictions .