Just an update - Horse Track opened a few weeks back. The track maintenence crew have done the steeper pass section around the gate and are slowly making their way down the more gentle parts, but it's all been brushcut and is an easy walk, the steps they've done so far are top notch, too.
Speaking to people in the know recently - and I have been hearing the same for a few years - NPWS will basically make Horse Track the advertised way in and encourage people to use it as a main route to Acacia Flat. They are leaving the Williams track (from Govetts lookout to Junction rock via the base of the falls) alone for a good while due to landslide risk, although it's interesting to note that the new valley floor signage has directions, even though there is very clear "track closed" stuff up at Junction Rock. So it's "never say never" on that part. However the Rodriguez pass up Greaves Creek to the Grand Canyon will never re-open. In particular the section pictured at the top of the page has completely dropped away, leaving the cable rail floating in mid-air.