I think that having only the black templars is the best way to go. Besides cameos of other chapters, it really would only make sense for them to have one chapter at the most. The only other time anyone post-heresy would join up together, chapter-wise, would be when they had to take out a HUGE waagh/huge Daemon Prince/tombworld, (Armageddon anyone?)
Anyways, so unless Vigil is going to have a badass nemesis similar to Ghadgskullz and his Waagh!, then I can't think of any reason for them to have more than one chapter. They said they were focusing on your heroic story, so I am assuming that having other chapters would minimize an individuals importance.
But then again, the game is nowhere near out and I could be COMPLETELY wrong!
