The New Small NarrowBody (NSNB) that guppie mentioned. Only the CS100 (now A220-100), E190, or E195 qualifies.

If they put 88 NSNB on the line flown by UAL pilots they can have 70 additional 76-seat aircraft at Express. Fewer than 88 NSNB and there's a ratio for how many 76-seat UX aircraft they can add.

The 737-7 has not been mentioned in the reports and rumors as additional MAX orders and the 737-700s are the oldest of the 737s. They could do 88 A220-100s for scope then additional A220-300s for 737-700 replacement/expansion of that gauge and to increase the average seat-count on the fleet an appease the accountants. I think that's a good rumor. Let's start it!