Krazy, regarding an additional themed area behind Roaring Rapids, I think it is HIGHLY doubtfull it will happen ever, or anytime soon. That road is the employee access road and it could be moved, if needed, however, that field is adjacent to many many houses. It kinda acts as a noise/space buffer between the park and the neighborhood. FYI, the park does own that land and I'm pretty sure they own the lake across from Shockwave.
So, why not build there anyway? The reason that will not happen is because of the neighbors that protest each and every ride SFGAm ever attempts to build. Since all the new rides are inside the park, construction moves forward without any problem. If the park wanted to build a hige coaster adjacent to the houses, however, I don't think they would get permission.
At all of the city board mettings, distance between the houses and the planned new coasters is always the biggest topic,
With that said, dont get your hopes up.
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Coasters are fun
Coasters are cool
and oh yeah, I like 'em