You can leave from Fortesque Bay and walk to Cape Pillar but are not supposed to go towards Mt Arthur. So can do it partially as a 2-3 day walk depending on your pace. The original campsite is still there, and has platforms. If you need water should be able to get it from one of the accessible huts.
Parks also ask that the track over Mt Fortesque is only walked in the direction towards Fortesque Bay.
In summary the 'original' track route is still accessible, and upgraded from Cape Pillar to Fortesque Bay via Mt Forteque, but not the new towards Mt Arthur.
https://www.flickr.com/photos/118621459@N03/albums/72157680286260835