But you said yourself that in your scenarion Austria would be allied with South Germany. And you conviniently forget the Ottoman Empire. Sure, WW2 history is much better known, and the Ottomans didn't exist by then anymore. But still, the Ottomans went to war against Russia by themselves, and were actually allied with Germany and Austria in real life. Also not to forget, not that long before WW1 Britain and Russia went to war over Crimea.
But sure, if your world looks better when everything can be blamed on Germany since, at least, Bismarck, by all means go for it.
Regarding Germany confidence, I mentioned that more than once, didn't I? Germany had one shot, they tried with some variation of the Schlieffen plan. They failed, but were too comitted to stop. Not that the Entente wpuld have been ready to negotiate a peace treaty to begin with.
But let's speculate, and pick an other evil war mongering nation responsible for the misery of the world, one that is equally redicioulous. The British Empire. Had Napoleon not tried to defeat Russia, but instead comitted to defeat the British in Spain, he could have formed a united nation in central Europe out of France, Spain, the various German Kingdoms and maybe even Austria as a very close ally. As a result, no German nation to behin with, hence no Hitler and no WW2 in the form we know it. So, the Brits are at fault, especially Wellington withbhis audavity to defeat Napoleon at Waterloo! See how that is completely laughable? History doesn't happen in a vacuum, and it did happen the way it did for a reason. What ifs are completely pointless, understanding why things happened the way they is very important so.