I heard the same thing scoop and it came from somewhere other than APC. It was specifically stated that the company was sure if they parked the 747's then got more 777's that were flying the routes the 747 had been flying that they would be considered replacement aircraft and be subject to the fences. The specific I heard was the DTW base because they would need two categories, one with non-replacement 777's flown by fDAL and another with the replacements flown by fNWA. They figured it would be cheaper to keep the 747's until the fences fall down.