This game could write itself! Hyrule (The Zelda world) is very unique and has been explored in detail through the various Zelda video games. Races, locations, magical object, world mechanics, even historical timelines are well established and ready to go for an RPG.
The demand for a Zelda RPG is so great there are multiple fan sites that have created independent versions of a Zelda RPG such as http://www.zrpg.net/.
So if the world has been given a Zelda cereal why are we still waiting for the RPG?