I have seen a lot of positive posts here about the HKG QF lounge and I don't really rate it, the BBQ pork is nice, but it is a very small serve.
It makes sense to me that if you are QF and there are other F lounges in the OW group that your money could be better spent elsewhere.
As far as BNE is concerned, like AKL I would gladly take a lounge that is a half step between a Business and First lounge over their current F offerings.
I don't have a problem with the concept of a premium lounge which is essentially a J lounge with some F lounge touches.
It does make sense if there isn't enough demand to satisfy separate F & J lounges.
Someone has said Finnair does this concept well.
I do have a problem with replacing separate F & J lounges with a J lounge which is labelled a "merged" premium lounge if that label is just spin.
Champagne isn't even an exclusively F lounge thing - Emirates serve champagne in their J lounges, as do many airlines.
I do think Qantas should be offering champagne in its international and domestic J lounges and in J cabins on all flights.
As for a really merged premium lounge ... it should offer some of the services you would expect in an F lounge.
My suggestions would include - an exclusive area within the lounge for F or equivalent status pax, with (better) champagne.
If policing access would be a problem then service at the bar could require a boarding pass.
Superior shower suites with the magic cupboard pressing service for F or equivalent status pax.
Spa or massage services with one free service for F or equivalent status pax and additional services at a cost, and any service at a cost for J pax.