Let's make some rumors come true with this thread!
So how about: A massive themed water park inside a fully temperature controled building with an enourmous "Hidden Mickey" solar array on the roof powering it all, heating the water, and being the park's icon. Local crowds and APs would have a place to go on a rainy day. The tourists might start adding more days to their trips. Indoor water parks can operate 365 days of the year. Disney sells more Corn Dogs and T-Shirts.
DLR currently owns some prime real estate at the corner of Disneyland Drive and Katella, I think it's the Downtown Disney parking, but I'm not sure. In that location the water park can easily tie into DCA or either of the hotels on that side of the street. Might require building a new garage but that's inevitable.
I was thinking a Toy-Story theme would work great, giant garden hoses and Hot Wheels tracks for water slides. Or maybe a 20,000 Leagues themed park with an interactive giant squid that scares you in the wave pool! Perhaps an Incredibles meets Marvel meets Ariel mash-up... meh... Maybe they could squeeze a replica of Hawaii inside a building with a retractable dome and theme it all to Lost.
Lot's of possibilities here! What other ideas do you all have?