One thing I would expect to stay for standard domestic catering is the bulk-provisioning of F meals, as they are now. Typically, airlines pay caterers a fixed rate per tray setup, which increases per item as other things are added to the tray. Boarding stacks of plates and food items (like sandwiches) in bulk is cheaper than ordering a cart with, say, 16 entrees loaded in an oven carrier, 16 tray setups, 16 salads, 16 silverware rolls, 16 water glasses, 16 s+p packets, 16 desserts, etc., per flight, which are charged on a per-item basis.

Delta's revised (2019) international Main Cabin service is bulk-provisioned and while marketed as an enhancement, it is actually a less expensive product to cater. UA is probably now developing a way to relaunch domestic F catering, post-COVID, in a way that will look and feel a bit more premium than the current interim product, but definitely cost less to deliver than the standard pre-COVID service.