I think what happened was that Nojima wrote the drama and novella with the intentions of continuing with an X-3, since he expressed his want to do so. However, the incredible backlash against the material put Square Enix off the decision. Not even the Japanese fans liked the new add-ons, and they were pretty okay with the XIII sequels from what I've heard.
Think about it: a few days before the HD Remaster's release, Nojima expresses his positive opinion of a new entry, and even says he has a full idea of what the story would be like if it ever came to fruition. Then all the negativity and controversy came, and now SE comes out and says that the new material was just to 'expand the world of Spira'. It really can't be coincidence.