It would take about 3x the starting pay, repeal of the RLA, pilot pay based on something other than # of passengers, the major airline with their name on the CRJ being held accountable and liable for the regional's operation (unless they decided to take the name off and not call it by the major's name) and a total overhaul of the seniority system (possibly doing away with it as it's currently known). I see the fine women and men of the 121 world piloting their airliners every day in my job and I can tell you there is no real difference between someone flying a dash-8, 737 or 777. Flown a little differently, but not enough to make up $250K difference in pay, not by a longshot.

Of course for these things to happen, it would likely mean a downsizing of the industry, majors taking more routes back, less service to small hubs where people can drive in a reasonable distance to the major hubs, and so on. The industry has been artificially inflated for a long time now, supporting the demand because the product can be offered for a certain price. If that price changes, the demand for it will change too and the industry will have to adapt. IMO there's a fixed amount of demand at a certain price. The thousands of parked airliners in the desert tell me the demand is just not there, or at least being artificially supported by the regional model.

Of course, I don't think the stuff in the 1st paragraph will actually happen, more than likely the regionals will just start to crumble and implode, possibly resulting in many similar outcomes, but to a much lesser extent and without ever making the overall changes that would bring back so many people. That's kind of it though, the demand doesn't really exist IMO for that many pilots. The demand only exists at a certain level, which if it can be sustained, is pretty much only good for the executives.