Just looking at whats publicly out there I would venture a guess that ExpressJet could very easily end up an all 175 fleet at the cost of MESA unfortunately for them. I think any United owned 175 is going to ExpressJet. CommutAir will take all the 145s it can staff and ExpressJet will end up with about 100+/- 175 air frames total. This is probably why they are not freaking out with the shrinking of the pilot list just yet. MESAs CRJ700s will all be converted to 550s and probably sent to GoJet ( unless MESA owns them??).

I am even going to wager this will all happpen by mid to late 2021. United just has way to many untied strings blowing in the air right now for major shift in flying not to happen. Once United gets a better handle on what the new pilot contract is going to be they will fully pull the trigger.

Just my opinion looking at it from a pure business prospective.