The majors could solve both their feed shortage and retirement replacements in one move. Start ab initio training like some foreign carriers do. Once the ab initio program is in place the only hiring comes from their 0 to hero pilots and everyone still in the regionals is stuck there for the duration of their careers. Not only does it stop the bleeding at the regional level but it ensures the regional feed for the next 30 years.

I should be a CEO somewhere.