For one thing, Civilization would have to use Frederick the Great as the leader of the Prussians.
In this case, I don't think the theory of one indispensable man applies; rather, a secondary light (at least in OTL) would have stepped forward as the ostensible unifier of Germany (don't recall who, though). I also don't buy the argument of the vacuum caused by no Bismarck would permit Vienna to swallow the rest of the German-speaking jurisdictions; I can't see the Protestant Prussians, for example, sitting still for this.
But a non-Bismarckian unified Germany would probably have had something of a different, more liberal government, with less power vested in the chancellor and more in the Reichstag. In turn, that means that Wilhelm II's vagaries would have been more subject to review, comment--and perhaps veto.