I've also heard this too, and actually seen a claimed proposition for the plans for the resort. Here they are... (see below). No idea if this is fake or not, but seem to be extremely plausible plans. They are very well detailed and well thought out.
The reason river country closed was due to a safety issue and an assumed parasite of sorts in the lake it was connected to. The site is still there and is very very rundown. You can see in many
youtube videos of people who seek past the gates from fort wilderness. I bet its just one of many many rumors that have come out about river country since it was strangely abandoned and not demolished, just like discovery island in the middle of the lake(at least i think thats what it was called) which has a weird story of its own. Ill let you google that one if you want theres a news story and images of a swim to the island and some outrageous, but real pictures of the island itself including the extent of its abandonment. There was everything from pictures of employees to certain electrical things still being active which was very strange, but it is all mostly rumor about the island that was confirmed.