To Expand on the previous post:

As of Right Now
Classes for Majors:
Alaska - Postponed classes
Allegiant - CX
American - CX / Asking for early retirements
Delta - CX
Frontier - CX
Hawaiian - None scheduled
Jet Blue - CX
SouthWest - None scheduled
Spirit - CX after April
Sun Country - Reduced size of classes
United - CX

Classes For Regionals: TBD = Can't find 100% definitive information
Air Wisconsin - CX after April
Compass - Closing
Commutair - CX
Endeavor - CX
Envoy - CX
ExpressJet - Hiring
GoJet - TBD - I believe hiring
Horizon - CX
Mesa - VLOA
Piedmont - TBD - I believe hiring
PSA - TBD
Republic - CX
SkyWest - CX
TSA - Closing

** since AA is looking for early retirements, potential for flow backs to their wholly owns is on the table as well. Keep that in mind with Envoy, Piedmont and PSA