Anything can be better than the current pathetic offerings. Just visit the SQ Business Class lounge (not their lower standard *A lounge) and see what QF has to do to stay competitive.
I can't comment on the SQ J Lounge, but, I did find the QF SIN F Lounge, well, pretty basic and the QF J Lounge pretty good, and by my opinion, better than the F Lounge. The bathrooms/showers in the J Lounge were fantastic.