It does not make an any sense to me. I would definitely get the D600 or D800 for wide-angle landscapes. You can always replace it in the future for future FX model (if there are really good reasons). If you are concerned about QA issues, take it easy. Most likely you will be fine. Make sure to get the camera from reputable seller with good return policy and don't shoot too much sky at f/22 in first couple of weeks.
In 99% you will be fine with perhaps one cleaning after some time (I always send my cameras to check&clean service to Nikon every year anyway).
The number of AF points is not an issue. The difference between 39 and 51 on FX is small. It is the FX vs DX thing that makes the difference. Anyway if you are shooting landscapes you definitely want to use liveview that gives you ultimate focus accuracy, unlimited number of AF points and no FF/BF issues. I don't think that future FX cameras will be able to give us significantly better AF coverage unless they fundamentally change the technology.
I would personally never replace 12 additional points for limited wide-angle lense options and especially cropped DX viewfinder. Especially for landscape photography.