Probably never. It would be necessary for Nikon to add support to its SDK before Adobe would be able to provide tethered support in Lightroom. At this point, it would seem unlikely that will ever happen. It would be unlikely that you would ever get Nikon to comment, and Adobe doesn't make announcements on future plans either.
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With your images downloading into a DigiCamControl "Session" defined folder, you then set this folder in Lightroom for Auto Import. (Note: it must be empty when set up in LR)
With both software working- camera shots will then automatically import into the Lightroom catalog