The thing is that The Walt Disney Company has changed a lot. They're really trying to get as much money as possible by remaking movies or sequels. The same goes for the parks, they rather want to place a 'bigger' franchise in the parks, because coco isn't one of pixar's most populair movies. If they're going to build it, I would expect it to see it going to DCA or Paris, since they had the chance to build it with the epcot overhaul, but they didn't.
(That's what I think, it is probably wrong tho)