I think, at least from a watch point of view, any ruling would only affect the grey market in the truest sense of the word. The correct definition of grey market (although it has seemed to encompass all resellers of Rolex) is buying a watch overseas, importing it (taking advantage of currency fluctuations and local taxes), and then selling it. This is different from a reseller trading using watches sourced within the country they are based
I can't see how it would be possible to stop a person deciding to sell their own property, and I doubt a watch company would want to deal with the negative publicity that would surround such a decision. I wouldn't worry too much, unless you were planning to set up a watch importing business