Disclaimer: Nothing is inevitable with an early enough point of divergence.
Obviously, the Prussians were the main driving force behind the unification of Germany, with Austria losing to Prussia in the war they had in 1866. This led to the formation of the North German Confederation, and soon Germany at the end of the Franco-Prussian War.
But even if things were to go badly for Prussia, then Austria, or even Bavaria, could have rallied together enough states to form Germany, right? I wonder how much would have to go "wrong" for Germany to never form. Seems like it would have to be quite the divergence.