Yea it's an annual cap of 120,000 points but the little known loophole is that the Qantas version of the card still earns 1 QFF per $ spent at Qantas even if you reach your 120,000 annual limit.You are correct. I had originally though that but on receiving the card I decided to recheck and must have misread the terms.
www.hsbc.com.au/content/dam/hsbc/au/docs/pdf/pp_rewards_terms.pdf
Clause 6.4 of the below says you won't earn any ordinary [Qantas] points beyond 120,000 per year, but clause 7.2 says you will earn 1 bonus [Qantas] point for every $ spent at Qantas. Since HSBC make a distinction between ordinary points and bonus points, it means you can still earn Qantas points beyond the annual cap albeit restricted, but still possible.