I have a question.
Would it be legally questionable for a 3pp publisher to release a PDF product that contained re-named and mechanically-different but thematically-similar races equivalent to Eberon's warforged, changeling, shifter, and kalashtar?
What about a product that contained a bunch of mechanically-different feats that gave you "marks" that, depending on your race, gave you special powers related to a theme?
Again, in either case the mechanics and names would be completely different from the mechanics and names used in WotC's Eberron Campaign Setting. The tone and theme would be near-identical, and clearly inspired by the material first published for the Eberron Campaign Setting.
Surely WotC doesn't have a copyright on the idea of hereditary tattoos or half-dopplegangers. Would such a product be legally legit without the express consent of Wizards of the Coast? Is there a precedent for such a thing?