There is support in the release candidate for Camera Raw 8.6 as well. So that should be an indication that native support for your NEF files will be available in the next Lightroom update. I would guess that update should be available soon, probably within the next few weeks. But you will just have to wait for the update. If you keep in touch with this forum you will know when the update is available as soon as anyone else does.
I understand your need to have Lightroom support your NEF files. But, in the meantime, (I'm going to mention it again) that DNG converter release candidate will enable you to work on DNG copies of your files so that you can evaluate how things are going. You'll still have the original NEF files that you can go to as soon as Lightroom supports them. I know it isn't the solution that you want or need, but it will at least give you access to your raw data now.