When I have previously asked why Nyrstar persists with the inefficient loading of zinc in trucks at Risdon, roading to Hobart, only to be unloaded / reloaded into containers and onto rail, to be hauled almost back past where it came from, whilst the rail line direct into Nyrstars plant sits disused, I was advised that it all is due to the warehousing arrangements at Risdon, where (reportedly), the most recent warehouse was constructed physically across the old rail access (well THAT was clever planning, wasn't it!) and is only set up for bulk loading into trucks (i.e. no room for packing in containers - hence the need for doing that at Mac 5 (and likely soon to shift to Brighton).
So, to facilitate the re-use of the Risdon line, the following would need to occur:
1] The existing warehouse at Risdon demolished or rebuilt to accommodate rail vehicles,
2] Space found at Risdon for packing containers (in other words - a brand new warehouse),
3] Someone willing to facilitate / fund that,
4] Restoration of the Risdon Line and Tasrail being willing to resume long term usage of the Hobart Line as far Derwent Park.
Issues likely preventing the above happening would include;
1] The likelihood that Nyrstar are heavily restricted in capital expenditure and the costs to rebuild warehousing arrangements would not see a return in transport savings in the short time frame neccessary,
2] The disinclination of Toll to forgo their lucrative short haul transport from Risdon to Hobart (soon to shift to Brighton) and pending centralisation of their activities at Brighton,
3] The disinclination of Tasrail to upgrade and continue usage of the Hobart (Derwent Park) / Risdon Lines to gain another 15kms of haulage.
The only things that may precipitate a change would be a Govt funding package to pay for the rebuild of warehousing at Risdon, Toll taking control of the Risdon warehouse (or retaining control if they do already) and funding provided to Tasrail to upgrade and continue maintenance of the Hobart (Derwent Park) / Risdon Lines.
As much as I would like to see that happen, I would expect such a Govt funding package (especially under the Liberals) would be extremely unlikely (especially as it isn't likely to be a high priority lobbying issue from Nyrstar) and both Toll & Tasrail would prefer to consolidate zinc stowage and loading at Brighton (unfortunately to the detriment of the Brooker Highway).
The only thing that would potentially turn that on its head would be if Nyrstar finally decided delivery of ore by ship from Burnie / Port Pirie was no longer viable (e.g. ship replacement costs, crewing / fuel costs, etc.) and decided to turn to rail delivery from Burnie (which raises issues of Nyrstar requiring a blend of Rosebery / Broken Hill ore, rather than 100% Rosebery). The major restructure at Risdon to accept ore deliveries by rail would then make zinc dispatch worthwhile for both Nyrstar and Tasrail.
However, my expectation is the likeliest fate for the Risdon Line is to become a branch off the Inter-City Cycleway, like the Cadbury's Line.