While UA might have a reason to want US out, I would assert that the European carriers, especially LH and JK, have a vested interest in the success of US.

US feeds a lot of connecting traffic to LH in PHL and CLT and gaining the HP cities in the west actually strengthens that positions. As for JK, they offer a lot fo connections options out of MAD so they too have an interest in keeping US in *A.

I agree this was just a worst-case scenario for a 10k filing. I'm losing no sleep over this. Besides, even if US were to leave *A there would be a warning period so we could cash in our miles and take off like lemmings to UA.