User blog comment:GinIchimaru/Hogyoku-Possibilities now/@comment-452405-20100426112005

I wonder if he's even gonna bother with bankai this far into it. Maybe he's forgotten about it with this whole focus of turning into a god.

Or (now for my daily completely random theory) perhaps his bankai is controlling peoples five senses and that how Isane described his apparent shikai actually was his shikai, what was it again? A mist used to confuse and cause your enemy to attack each other, I think controlling five senses as well as he does without the need of the initial mist is a reasonable step up from shikai to bankai.

Again, just speculation that could be proven false at any moment. Like why would he need a release command for bankai unless it was just to maintain the illusion of it being his shikai.