[@Renny]

[quote=@Renny]
[@jynmi88] Something like adaptive Zanpakutos? I need more info on that, even if its not concrete. I'm curious now. 
[/quote]

Well so far there are two possibilities I can think up.  There's a third that I played around with awhile ago that was the empty hit stage but instead of a sword it came in the form of an invisible armor that acted like a symbiote from marvel comics, but that might be changing things too much.  

1.  The zanpakuto never fully mature.  You know how once a bankai is mastered, and that's it, no more special techniques or new aspects?  Well, with these new zanpakuto, that's not the case.  Once the shikai is unlocked, it acts more like a devil fruit (One Piece) or quirk(My hero academia) which they constantly find or invent new uses for.  

2.  The zanpakuto's released forms reacts to damage, and battle situations, subtly changing after big encounters.  Though, for this, I'm not sure how it would effect the bankai as they only become weaker upon receiving damage in that state.  (except Mayuri's)