I think it might be a little too far to consider it something possible to being canon. The entire arc is just a big fan fic or fan service, meaning that it gives what a lot of fans have been wanting for a while. To see what everyone else's Zanpakuto manifestations are beside Ichigo, Renji and Hitsugaya. Though I think all of them being human is inaccurate. I think a lot more of them would be animal in nature. So I have my doubts if you could even think of the ones appearing as being true representations of their Zanpakuto. Some definitely, but the rest I don't think so.

Its a better and more interesting idea than the Bount Arc, but it is still filler and I'm not really going to think of it being canon or possibly being canon. I'll stick to the manga.