Now, I'm not saying a whole filler arc is needed. But when I say filler for this arc, I mean extras that can be added to what was in the manga. Things like:
Seeing more of what Unohana's Bankai does.
Seeing full transformations for all Quincy.
Getting the Bankai of the Vizard.
The light novels animated (Showing us Shinji's & Hisagi's bankai)
Showing us Urahara, Yoruichi and Grimmjow's escapes
Yoruichi & Squad 0's Shikai & Bankai
Anything else you guys can think of?