This might also be a possible knock on effect from the 737 Max grounding which will extend to Jan. 16. We had the nonstop from JFK booked on AA in March and, with zero notice, our flight was changed to an extremely inconvenient connection in LA that had us arriving 10 hours after our original plan. The frustration was no notice, but I did get a refund easily and rebooked on JetBlue.
Although we were not scheduled to fly on the Max, they seemed to be repurposing planes to hubs and LAS isn't as big a draw in early January as, say, the Caribbean.