As has been stated above like improvements to the Highway each components adds to the whole.
The quantitative leaps that Us railfans would like to see can not always be matched by Government expendature. Pitty.
Way back in 1992 the need for an SSFL or equivalent works was flagged as a national transport priority. Nothing came of it until ARTC took it on as part of the NSW Lease. NSW showed no interest in quading or building a dedicated freight line themselves. Given it was a separate line it became an all ARTC show (unlike the NSFC works). Subsequently NSW handed over the metro freight lines that connected with the SSFL.
One can speculate but it's unlikely anything would have changed without ARTC in the picture. Presumably as metro passenger traffic increased, there would be fewer paths and operators would have nothing like the flexibility that the SSFL provides.
NSFC scope was dumbed down considerably. Funding was provided for 1 project on ARTC and 3 projects on NSW controlled lines. It's unlikely to be a game changer.
Precious little guvmnt funding has gone into the DIRN since 2010. There is no indication that the feds have any intention to provide significant funding for any rail improvements into the future whether they be along the existing East Coast line or some inland railway. In fact is there a national strategy for rail at all