There are not many domestic USA routes on which an A380 or 77L operating 1x or even 2x daily makes sense. Consider that zero, nil, none, bupkis, nada, not a single US carrier has purchased an A380, or are going to, and how the Big Three have pretty much given up flying widebodies to places like Hawaii, save for markets that cannot be reached by narrowbodies, and you get the idea. EK's model and fleet is not meant to serve internal USA markets; it's meant to serve DXB as a scissors hub, and use it to connect places like India and Australia to the world. It is a good model for that.

The airlines the Big Three have to fear in the US market if cabotage was eliminated aren't EK and SQ, they are AK, DY, FR and U2. They would set up 737/A320 bases and start shredding market frequencies in key markets in a heartbeat, with lower-cost labor and lower costs, and able to pick off the price-sensitive people who make high frequency flying and hubs viable. This is basically the same model NK is using to good effect, and that F9 has transitioned to. It's worked for all of those airlines. We're starting to see this already in the TATL market from DY and WW... with EW to follow.

Service levels on the plane are entirely different creatures from loyalty programs outside the plane. Go look up what EK offers for RDM/EQM on their discounted Y fare if you think that somehow their hypothetical service in the North American market is going to usher back in the days of massive amounts of miles sloshing around if you buy lots of cheap Y (or look at SQ's program)... if anything, the outsized returns on Big Three loyalty programs were basically bribes for less competent service ("suffer through our lousy planes so every so often you can fly and enjoy some caviar and Krug"). Once those golden handcuffs are taken off... let's see if the Big Three can sink or swim.

(It's not like EK is some kind of paradise in the back... 10 across Y in 77Ws, and 615 seat A380's don't sound like much fun to me.)