QF got rid of the curtain some years ago when they refurbished the seating. There is now a plastic divider behind the last row of C-class (theirs is a fixed cabin with armchair seating) but also no curtain. They make announcements to encourage people to use the right loos but given the meal cart blocks the aisles for much of the flight it is an ordeal for those at the front of Y-class. Crew try to enforce but it is difficult for them as some of their most frequent flyers populate those front rows in Y.
Virgin Australia's rope attached by magnets seemed to do the trick.