First I totally understand - and agree with - the frustration with Nikon for changing its repair facilties options. I have used APS many times and been very satisfied. But Nikon, Canon, Sony and other manufacturers have always had the right to change where and how many repairs centers they authorize. And Nikon has NOT suddenly changed its policy on grey market items. Companies make changes all the time to doing work in-house, then out sourcing it, then bringing it back in-house!
However, I don't believe Nikon's position on grey market items is very different than that of Sony, Canon and other major manufacturers. A top Canon pro, and very good friend, says Canon repair approaches are also changing.
I found this information - which I
think is correct....
"Sony, Nikon, Canon, Panasonic, Fuji etc. will NOT honor the warranty on any goods not bought from an authorized USA dealer - and this is not just on camera equipment. That's the whole point of being an "authorized dealer" - buyers get warranty coverage.
Grey market. What are the rules? Simple really assuming that you are buying from an authorized dealer.
If you need service it needs to be returned to the country it is warranted in. So if it was warrantied in China it will need to be returned to China. If you need to discuss the return, good luck finding a Chinese rep that speaks English.
This is different from purchasing an item while visiting a foreign country. If you buy it while visiting a foreign country the warranty is transferable. This allows travelers to purchase merchandise while traveling abroad, but the camera menus are generally tailored to the country you are visiting. Talk to the retailer in the country you are visiting."
When I first started buying lenses, I scoured the photo magazines prevalent at the time. I researched all the ads in the back of the mags, comparing prices of both USA and grey market items from camera shops all over the country. What fun - I would spend hours planning my next acquisition!!!!

I also read the fine print on "grey market" lenses that those mags had buried in the magazines. And fine print it was! Then I read a lot of user comments and talked to dealers. I got some favorable but mostly wary advice regarding buying grey market items. I decided
for me, saving a few percentage points on price was not worth the risk of getting repairs and facing lower resale values on grey market items. IF I were to take that risk, it would only be on low valued items, not high priced items.