I am not sure that I would even agree to a codeshare until US gets its house in order. US has a storied history with primarily negative stories (with the exception of Piedmont and PSA Airlines). Certainly, Allegheny Airlines (predecessor to USAir) was called "Agony" for a reason. USAir dropped a lot of the routes of Piedmont and PSA, after seriously building up on the West Coast. Except for a few good years in the 90's, I was never enthralled by US Air (poor operations with a lot of excuses).
HP should run away -- VERY FAST -- from this merger. The only way that I would agree to this is if you could negate all the contracts and decide which US employees to hire. Plus, the labor cost would have to be very similar!