Well, Juha Bach's avatar isn't necesary a bad guy per se. Ichigo's Quincy powers might have taken the shape of Juha Bach, since Ichi is half Quincy, but it seems we will learn more details about it in the upcoming chapter.
My point was that Ichigo was always thinking that Old man was the true avatar of his Zanpaktou and was always fighting against his White thinking that it was a foreign power, an intruder, always feared him, but in the end it was his true Zan's avatar, so of course, when he learns about it and accepts it, he will achieve stronger and more consistent bond whith his Zanpaktou. It's quite logical and consistent, according to managa's logic so far.
I believe it's obvious and logic that his Shinigami powers won't go anywhere, but they are mostly related to his body, not Zanpaktou, so I believe his Zan will contain either only Shinigami-Hollow powers or will either have a bit of Quincy powers. While his body will contain Quincy powers as before.