Playing Devil's advocate here...

Remember, Delta is NOT required to park any 50 seat RJ's if you don't ratify the new TA. Nothing is stopping them from renewing contracts on 50 seat lift and maintaining the fleet at its current size. Just because leases and contracts expire doesn't mean the airplanes go away.

Yes the 50 seat RJ is a not well liked and has a high CASM, but if the company doesn't have alternative lift, they will use what they can get.

I'm not trying to persuade anyone one way or the other on your TA; just pointing out possible scenarios.