QF has been doing this for 20+ years, ever since P was introduced as a 10% surcharge over F fares. Exactly the same idea, some flights had P with better service of some sort at a higher price, and some flights were F. SQ is doing it with their J+ fares on their ultra-long-haul flights (but their "cheap" J is skybed and the surcharge gets lower density seating).

CX has flat beds on some flights Japan-HKG and most flights HKG-Australia (but not all), and it does add several hours to the travel time but is a pretty good alternative. Fwiw, JL has long had 2-tier J and F services, differentiated by route but not by price (with a big difference in quality between routes of similar length). So this is probably a JL initiative and part of the Oneworld joining process; I wonder what anti-trust rules apply and whether the ACCC has jurisdiction?