Only Kirby and a few others really know, but when he publicly says that the 50 seaters will mostly be gone, I’d guess that he means most of them. In the few articles that I have found talking about this, they all seem to be glad to see them go. One article even called it “a positive note”. I understand that people will be out of work if this does happen, but this was going to eventually play out. Companies like Air Wisconsin and Expressjet are flying an old aircraft with no available replacement that the customers don’t like. The 550 is also a 50 seat aircraft, but it is roomy and has dual class. My guess is that they are the last to go.