I think OKW was a trial run. If they got the response they wanted, they will probably extend the other resorts.
However---that also depends upon what future plans Disney may have for those locations.
Remember that OKW is a stand alone campus, the others are attached to regular hotels...so Disney may want to keep their options open on those properties for re-development or replacement of the hotels in the future, and a longer term DVC lease may prevent them from that.