This is kind of what I was thinking too, but one thing confuses me. If they don't backfill FO's into Denver to replace senior & middle FO's taking east upgrades this will begin to create an uneven CA/FO Denver list.

Presupposing a balanced list is preferred, a decision to keep DEN status quo will require backfill FO's - the only other option is to allow DEN to shrink with eastern growth, but then this will conversely require Jr. Captains to be displaced to keep the list balanced.

Wonder which it will be?

I would imagine early on, the new base(s) and Chicago won't need to be huge, so it makes sense to keep Denver status quo, and grow the new ones with new-hires and upgrades. My theory is in the short run this mitigates risk & cost involved with displacing pilots to untested domiciles, and avoids real costs associated with Jr displaced Denver CA's bumping back to DEN FO.

However, I wouldn't imagine this careful approach will last forever. Eventually as fleet size grows, the 'outside of Denver' markets now with a history of viability will spur greater bolder crew placement decisions. By then absorbing costs associated with displacements will be a necessary cost of doing business.

Just thinking out-loud.