Yes Steve, the initial reason for this work is to get export containers out of Northland onto rail, but the Marsden Point branch will also be extremely useful in diverting the logs from the far north off the roads and onto trains. And yes it may even be useful for trains from Dargaville to the port although I tend to think the distance may make that a very marginal operation.
For the moment I would only advocate moving the car import business north from Auckland. It takes up a lot of space for a port that can only expand onto more reclaimed land which is not a plus factor for those who love Auckland's harbour.
But whatever, the revitalization of the railway is a plus that whatever else you think of Winston, is good for the railway.
ps, the really difficult one will be to persuade the people of Gisbourne to give up their port so that railways in that region can be developed. I am not just thinking Napier to Gisbourne but also the Taneatua line and its possible extension to Opotili.