Facts of (after)life:

1. The Seireitei (not this or that division, the Seireitei as a whole) does not care about every single mortal that might die. Dead mortals are actualy a good thing to the spirit world, to an extent.

2. The same applies to Las Noches and, for the fact, most other hollows. They shouldn't care for the mortal world any further than it is the source of their food.

What do these two mean? Other than the fact that your average captain or vice captain will never go down to the mortal world and even when they do they will go with 80% of their power sealed off. When captains, vice captains and espada are striding down to the mortal world, then there is big stuff happening.

Mediums fighting wild hollows? That's not big stuff. Should interest 12th division and whoever the science espada ends up being. But not much else.

Mortal World will be mainly the mortal's turf, with a few tethers linking them to the other planes at start (Reene, shinigami patrolers) but Las Noches and the Seireitei have two entire other dimensions to worry about. So lets ignore those two form the mortal world talk and think "what will be happening on those two other planes?" later.

One thing that I know will be happening? Von Geister will be hunting rebels. Like Elder.