I work in one of the finished buildings, so this is probably most up to date information.

The plan has been reduced dramatically just like any other ambitious Korean government projects. The size of the theme park is decreased significantly, and even the allocated land (163,174m squared) is now shared with a hotel, healing zone (probably spa complex), a water park, plaza, and a pavilion. Not sure if there will be a theme park built with good ride elements. Even concept art (second photo) does not include any rides. Some rumor was they are planning to build something like Wolmi Amusement Park which is just a park with carnival rides like the swing boat. I am hoping for a dark ride in the park, but neither city nor investors are interested in this project anymore.