I reckon that this white Aizen design is more like a "cocoon", it already has some cracks in it, I think it will break open to reveal Aizen's final form.
Either that, or Kubo is getting even MORE lazy and will leave it this way so there's even less lines for himself to draw. Bleach's art is already overly simplistic, he barely even has to put effort into it anymore IMO. He doesn't put any detail into anything, and he fills up large panes with pointless pictures so that there's minimal work to be done each chapter.
Someone already mentioned how Ichigo's fights are just black ink spashes as well.