Unlike UA, DAL has plans to replace them with MD-90s and 100-200 new NBs that I believe Richard Anderson said will be flown by DL pilots. NOT outsourced. The C-Series is one of the aircraft under consideration.

Since Jeff is so keen on copying everything DAL does, maybe he should consider ordering C-Series for mainline to fly and park unprofitable RJs

Delta Plans to Order 200 Narrow-Body Jets, Options for 200 More - Bloomberg