Unfortunately, it's not inconceivable that CX could go out of business altogether and this could be what the government in Beijing wants. Dividing the pie up between the Big 3 wouldn't be too difficult and having Air China operating routes from Hong Kong to London and New York sends a big message. If EK or SQ went under it would be a massive loss of face, and present immediate and long term difficulties for the city states. Losing CX removes a relic of the colonial era and capacity could easily be replaced by mainland airlines, particularly given the current surplus and aircraft available from the CX fleet.
Hong Kong is better located as a transit hub than Shanghai or Beijing, has an award winning airport and the city is an attractive stopover option. Using the city as a virtual hub keeps costs down. Back in the 1990s the Middle East hub airlines were just starting, now they dominate transit traffic.
At one stage prior to COVID, China Southern was the cheapest option on the Kangaroo route. Chinese airlines are pretty acceptable these days, a shorter travelling time with a HKG stopover and a low fare would be serious competition.