There was a ALPA member grassroots initiative in the late 70's in the face of deregulation to go to a nationalized senority system, but it was met with strong resistance by the MEC's.
It would have been much easier then with all the "airlines" at the major (UAL, DAL etc) and regional (Frontier, Piedmont etc) level being pretty much the same, and the independent commuters (Rocky Mountian, Air Midwest etc) being a different sector entirely.
Now it's all co-mingled and institutionalized to the point where IMO it's impossible.