As I would also like to see this come to the park, this is some of the excerts from "Celebrations" magazine issue 8, november/december 2009...
"When Walt Disney World opened, people complained. You see, for years, they had been hearing about this Pirates ride at Disneyland, and they were extremely disappointed that they could not find it at the Magic Kingdom. The complaints rolled in, and they piled in front of E. Cardon Walker, who became president of the company after Roy passed away. After awhile, Walker was sick of hearing it, and he did the only thing he thought would stop the complaints from coming in: He decided to build Pirates. (This pushed back constuction of the WRE) Then, another problem stuck a blow to the project. The Energy Crisis in the early 1970s wrecked havoc on WDW's attendance levels. It had been years since a Western film had made money at the box office, and the long running show Gunsmoke was ending its 20-year run on television. Execs also feared that the caricatures of Natve Americans would bring bad press to the company from the American Indiana Movement, which was quite popular at the time. When construction began on Big Thunder Mountain Railroad, it was almost like a nail in the coffin of WRE."
Of course, this is a condensed version of the article, but you get the idea. It is still on the backburner....so never say never.