Slow news period huh? So when is the live stream going to resume? I have mixed feelings about Legendarys just appearing randomly throughout the game, let me do a head count of the ones so far...
Regigigas ~ There is a picture with it in it
Regirock, Regice & Registeel ~ If regigigas is available, so are they
I would have to disagree with you about Regirock, Regice, and Registeel.
I think it's possible that Regigigas is available for capture in BW2, but not the other regis.
Then, if Regigigas is traded to the next two pokemon games released, it unlocks Regirock, Regice, and Registeel's locations.