I think that Falinesti, the last of the walking Graht-Oaks taking root some time ago might be a sign of a potential Valenwood game in the near future, though the same could be said of the Bosmeri prophet, which I currently believe to be ESO's Wilderking/Wilderqueen, promising new gifts for Y'ffre's favored people. There is definitely potential for a Valenwood game, with an adequate variety in locations, dungeons and settlements, as well as a main threat in the form of the Wild Hunt.
However, given a number of outside factors and influences, as well as its familiarity, I still think Hammerfell is the most likely province. It is possible that BGS weaves in some LOTR influences as they did with Oblivion and Skyrim, basing some things off Rh?n and Near Harad. The coastal cities, such as Sentinel or Hegathe I believe could be based off the city of Umbar, as well as several other real-life and fictional influences, namely the famous port of Carthage and ASOAIF's Free Cities and Dorne.