Confirmed that Old man is not Juha Bach but the manifestation of Ichigo's Quincy Powers. It also seems through the entire manga that all the power Ichigo had was simply just a small portion that old man zangetsu couldn't keep sealed. So crazy power up incoming.
For Ichigo's new Zanpakuto, Zangetsu is being replaced by... wait for it... the true Zangetsu! It was kind of obvious though as you have to remember Shirosaki always saying that he is Zangetsu.