I’m not sure the above comments are truly accurate. UA flies the 320 between JAC and SFO/LAX/DEN. So clearly DL could shift their flights to SLC and put an a320 on the route if they wanted. They could then shift some
319s or A220-series to JAC-ATL and add an extra frequency or two to cater to the southeast regional flier that doesn’t have nonstop SLC access.

DL may not really care about the forced loss of capacity. If all airlines have a similar problem it means increased ticket prices. DL wins either way.