Thanks, Speck, for posting this picture! It proves what many of us have tried to convince others of for quite a while...that the playground barely affects the actual 20K site, and that the land has been leveled for a new attraction.
The problem is... what attraction? Whatever goes there will make use of both the old lagoon and show building areas. A park-wide manager (meaning that he oversees the entire MK, not just an area) told me that an E-ticket attraction was once strongly considered for the site, but the budget was never approved; and the attraction never got past Blue Sky.
EDIT: Someone else already posted this, but I want to reiterate: Draining a former lagoon; filling it; leveling a show building; planting grass over it; constructing a very small, well-themed playground; and landscaping the area cost nearly as much as constructing a new attraction. Financing new rides takes time once a park is operating; Disney has to maintain everything that's already in the MK, pay everyone, and still get the budget for a new attraction. Replacing an under-used attraction that's in a prime location in Tomorrowland was simply more important (and less expensive!) than building something in Fantasyland.
