Just a thought. SS and the HUman realm are identical, but opposite. HM and Hell are both neutral. look at this picture:
SS would be north.
HM would be west.
Soul King realm is linchpin
HELL would be east.
HU would be south.
Right now all the pure souls are either in SS or HUman realm.
Impure souls are in either HM or Hell.
Only pure souls have weight.
Right now all the power is in SS so all the souls "fall" into that realm at death.
What if the HUmans(Quincy) attained more power than the shinigami?
What if that made the power shift and when you died in SS, your soul would "fall" into the HUman realm?
The Soul King realm is in the middle and is the fulcrum point for "existence" (linchpin). Everything hinges on it.
The intermediate points could be sub realms.
Dangai for example
Kyōgoku from bleach movie
Possibly everyone's "inner dimension" is a fragment of another
and the shadow realm where the quincies run off to.
Anywho, the current plot would be that the Quincy are trying to topple SS so that Human Quincies would be the new "gods" and Juha bach knows that the hollows dont effect the balance. He just wants to destroy the opposition, kill the hollows, and gain eternal peace.