Franz Joseph I of Austria
If Greater Germany was to prevail, the crown would necessarily have to go to Franz Joseph, who had no desire to cede it in the first place to anyone else. On the other hand, if the idea of a smaller Germany won out, the German crown could of course not possibly go the Emperor of Austria, but would naturally be offered to the head of the largest and most powerful German state outside of Austria—the King of Prussia. The contest between the two ideas, quickly developed into a contest between Austria and Prussia. After Prussia decisively won the Seven Weeks War, this question was solved; Austria lost no territories as long as they remained out of German affairs.
Austria–Prussia rivalry
Maria Theresa, still chafing under the loss of "the most beautiful gem of my crown", took the opportunity of the breathing space to implement several civil and military reforms within the Austrian lands, like the establishment of the Theresian Military Academy at Wiener Neustadt in 1751. Her capable state chancellor, Prince Wenzel Anton of Kaunitz, succeeded in the Diplomatic Revolution of 1756, allying with the former Habsburg nemesis France under King Louis XV in order to isolate Prussia. Frederick, however, had completed the "stately quadrille" by the conclusion of the Treaty of Westminster with Great Britain. He again took action by a preemptive war, invading Saxony and opening a Third Silesian War (and the wider Seven Years' War).