Great Wolf Lodge has been contracted to build a facility near DL. It will be interesting to see what happens when it's built.
If offsite resorts ever have success with better pool and water park facilities (Great Wolf, Kalahari, and dozens of other businesses), Disney will respond and add such facilities. Currently, they have no reason to do something like this.
If they branch out into any region with winter (such as DC), Disney would be wise to at least consider such a proposal. Resorts like the Kalahari, Great Wolf, Wilderness make a tremendous profit during the winter.