Clarifying. If A220s (flown by the majors) take over some 76 seat flying and 76 seat flying takes over some of the 50 seat flying, then some 50 seat get parked.

The ratio of 76 seat planes to all the planes at the majors would not increase. True, the ratio of 76 seat to 50 seat would increase. But if no more 76 seat planes are being flown, that would not violate many scope sections.

Where it would, I could see negotiations like this:

Today -
100 76 seat planes fly (RJ)
100 50 seat planes fly (RJ)

In the future -
50 A220-100 fly (major)
100 76 seat planes fly (RJ)
50 50 seat planes fly (RJ)
Same number of planes, same number of pilots
More lift (20% more seats for organic growth, those routes or other routes)
More pilots at the majors
Fewer pilots at the regionals
No more 76 seaters
Fewer 50 seaters

How would that sound?