User blog comment:Xilinoc/Ch. 650 - THE THEATRE SUICIDE SCENE 4/@comment-27106822-20151105183643/@comment-24531362-20151105212255

No Bankai thus far has had a power unrelated to the Shikai's power. So yes, according to in universe rules, there has to be a connection.

AFAIK, the power of Shunsui's Bankai is to make adult concepts like war, depression, and suicide into reality, just like his Shikai makes childish games and concepts into reality.