When I was there, significant portions of timber sleepers were still burning (as far as the eye could see) specially north of Roseworthy, I would have it a guess that the rail line through there are a total loss.
The line has been a total loss for decades, it is time it was converted to a cycle track to get cyclists off the main roads. There is nothing for it to do, next to no freight potential or passenger other than Roseworthy proposed new urban centre. Existing tracks are broad gauge. Just because the rails are still there does not make the track fit for purpose.