Its not just 50 and 76 seaters Delta wants. They are pushing hard to put 86 seaters and up to 11500 lbs MTOW at DCI (read Bombardier C-Series). I think the early and hard push is to get scope relief in exchange for $$$$ and put large RJ's at the bottom feeders.

http://www.airlinepilotforums.com/re...-proposal.html


Bombardier CSeries Gets Deal While Qatar Goes on Hold - Bloomberg

Bombardier list a "major network carrier" as the launch customer for the C-series with a firm order for 10 airframes and a delivery date of 2013

This is pure conjecture on my part but seems to me where this whole mess is going.