cxhk,
SQ was built up on the demise of many European carriers that use to fly down to Australia, nobody saw it coming when a small little fishing village placed the largest order in history at the time for 747s. Gradually all of those airlines ceased operating to Australia, and SQ went from a very small market share to over 20%. That 20% was a very big bucket, as that market has been growing. They even took market share away from QF.
Since the increase ME carriers into Australia, they have mainly been gaining market share at the expense of SQ, MH, and TG. SQ has lost the most market share, around 6% if memory serves.
Over the same period of time, despite operating more services, CX has maintained around 5% market share, it has no real growth or reduction in market share (the market has grown, hence the extra services). The market share has remained the same even with the introduction of many more services from China to Australia.
The most amusing article I have seen regarding Jetstar Hong Kong came from September 2013 edition of Orient Aviation. On page 8 the CEO Edward Lau was saying the airline is HKG run, on page 12 they have a large article with a summary of an interview with Jayne Hrdlicka (Jetstar Group Manager).
Jayne says in the interview she runs 6 airlines, including Jetstar Hong Kong. She said she will get their HK AOC in September 2013 and start operations by the end of the year.
The article goes on to say she has "104 aircraft under her control and a network of more than 60 destinations in 16 countries".
This really sums up the basic law point CX has been pressing, the control is not in HKG, and does not rest with any of the other local franchises either.