In 1917 the newly ascended (since November 1916) Emperor Karl of Austria opened talks with the French to get Austria out of World War I. It bombed because the Italians wanted more than Karl was willing to give, and also because his foreign minister, Czernin, wanted the peace to include Germany. Karl, OTOH, didn't give a fig for Wilhelm II and was willing to make peace separately. The French prime minister, Clemenceau, published Karl's letters and the basic idea emerged to the Germans that Karl was a "coward" and to the Entente as "treacherous".
As we all know, the Austro-Hungarian Empire was systematically dismantled at Versailles in 1918 thanks to the Entente (which led to a fustercluck known as Yugoslavia, and a landlocked Hungarian "kingdom" with an admiral as regent but no king (sounds like something out of a Gilbert and Sullivan operetta) among other things).
So, what if Karl's negotiations had been successful? I imagine there would've still been bad blood between Austria-Hungary and Germany about the latter being thrown to the wolves, but could it have saved the Austro-Hungarian Empire? How would Karl have set about ruling his polyglot state? Or would Karl have been dethroned anyway?