As for the new terminal and runway - well, what's better for HK? Cathay to expand or HK Express/ HK Airlines to expand? Over half of CX passengers are transit, adding nothing to HK well being. Almost all HK Express/ HKA passengers are either HK residents or visitors to HK, so either benefitting HK by giving them cheap flights, or by bringing in tourists/ business.
To add insult to injury, Cathay has cheaper fares in most markets than they do in HK, for a longer journey. I.e KUL-HKG-LAX is usually cheaper than HKG-LAX. Sure, there are reasons for it, but it doesn't argue for giving more to Cathay vs other airlines