I expect the next move for QF will be to remove F from the 744 fleet over time as the A380s come into service. I think that in 5-7 years time, the only 4-class aircraft in QF's fleet will be the A380s, with 744s retaining 3 cabins (J, perhaps with Skybed Mk II by then, Y+ and Y), and the 787s probably also with 3 classes (J, Y+, Y).
What is offered now in J, and especially with Skybed Mk II, is as god or better than F was 10-15 years ago. Y+ is looking similar to what J was when first introduced by QF back in the 1980s. So I see a cycle where F has grown to a point where it pushes itself out of the market except on the largest of aircraft (A380), and Y+ will grow over time to be the new business class.
This won't happen quickly, but this is what I predict happening over the next 5-7 years.