See.. This is where you screwed up. There are some on here that happen to deal with the marketing dept. @ mainline. You have not talked with them (radiant in your post) ; there are plenty of cities that mainline "needs" short term and with random frequency to be profitable and others that are just "off" of the overall hub pushes, yet still profitable. What "was" 50 seat flying WILL go away, cause 70 seat is more lucrative.
Problem is, most can't jump backwards & through hoops. DL's answer? The good ole "C-ya".
I stood back and watched for a while with plenty of laughs, but here, you are wrong in your viewpoint of how DL marketing works with DCI.
50 Seats will go, but only as a yield to 50+ seats. Attack me all you want, but scope will loosen. I hope to fly boxes myself, but it is what it is for the pax side. A "no furlough, 3% raise, keep section 28", will suffice. If you say "NO", you age yourself.
Cheers.