Reality check. Not going to happen.
PCL can only fly CRJ-900's for NWA unless PCL purchases them themselves (or DAL purchases them for PCL for that purpose).
Any acft in which NWA has any financial interest can only be operated on NWA routes/code.
From Chapter 1 of the NWA pilots contract (Scope):
B.7.c.(5) Except as to aircraft operated by a Feeder Carrier operating pursuant to the provisions of Section 1 B.7.c.(7)(d), any jet aircraft and AVRO-85 aircraft operated by a Feeder Carrier (i) which are owned or leased by the Company or in which the Company has a financial interest, and (ii) which are operated by Mesaba Airlines, Pinnacle Airlines, or any air carrier in which the Company or an affiliate has an ownership interest, must be operated at all times with the Northwest code designator (NW). If the Northwest code designator is removed from said aircraft, that aircraft shall no longer be operated by the carrier.