The 50 still has a few more years of service left in it, the transition isn't going to happen over night. They'll get interested soon enough if they want to remain profitable/competitive for contracts with the majors.

It's the majors that want to get rid of the fuel inefficient 50. XJT, TSA, AWAC and whoever else are workin on it, i guarantee it. I'm willing to bet they're just not releasing their course of action to the employees.