So, I think I might've posted a thread like this before, but I don't think it got much traction. If Charles VI, Holy Roman Emperor had a surviving son, say either his son Leopold born in 1716 or a boy born in 1724, instead of Maria Amalia, and if this boy survives into adulthood, one imagines this butterflies the pragmatic sanction. One also imagines this removes the Austrian War of Succession. Does this consequently prevent the diplomatic revolution, and Austria moving to ally with France? Furthermore, without the Austrian War of Succession, does this remove Silesia going to Prussia, and also preventing the loss of Naples and Milan for Austria?
Milan was never lost and second Naples was lost in the Polish succession war, before Karl VI's death. That being said, the easiest thing would be to have Archduke Leopold live to be Emperor Leopold II. However, the main problem behind the pragmatic succession still remains: Emperor Karl himself. He was hands down the worst Habsburg Emperor, if not the worst Habsburg monarch, to ever reign. He neglected the army, didn't bother to educate his heiress, engaged in several worthless wars that caused more harm to the Monarchy than good and to top it all off spent all his time getting pointless signatures not worth the ink they were signed with instead of strengthening his Empire to withstand the inevitable reneging that would occur at his death. Furthermore, you've merely removed Friedrich the Great's excuse to invade Silesia, not the invasion itself. Friedrich would invent another in due course, if not just outright invade without some kind of cover (which is what he basically did in OTL). In fact the only thing that's for sure butterflied is the reign of Emperor Karl VII: Leopold will definitely be elected King of the Romans before his fathers death, meaning no chance of a Wittelsbach monarchy.
So the real question is what effects does a male heir have on Karl VI's reign? The possibilities that exist are fairly great but again the issue is whether or not the Emperor will embrace them. For example, if the Emperor focuses his TTL energies on building up the army and filling the treasury, then Friedrich the Great might not be willing to make such a gamble and try for Silesia. Hell a strong army could also butterfly Austrian loses in the Polish succession war and/or the 1735-39 Turkish war. That would potentially leave the Habsburgs with Silesia, Wallachia, Northern Bosnia, Serbia and the Two Sicilies. It also opens the door on the Parmese and Tuscan succession: OTL Karl was very much opposed to the succession of Infante Carlos and sent troops into Northern Italy to block Spain form garrisoning the territories, opening the Italian theatre of the Polish succession war. Thus the potential exists for Italy to fall in its near entirety to the Habsburg Dynasty. I'm not saying that this will happen or its likely, but the possibility would be in play.
A second example is the Ostend Company. OTL it was the Austrian Imperial answer to the British, French and Dutch East India companies and in the decade or so that it existed the company provided strong competition for the traditional colonial trading companies, notably in the lucrative tea trade with China. However, it was suspended and then disbanded by the Emperor as the British price for recognizing the Pragmatic succession. TTL, with no reason to bow to British demands, the Company could and should continue to exist, opening up the possibility of an Austrian presence in the East Indies and India (specifically Bengal and Carnatic, where the Ostend Company establish factories OTL). Now this doesn't mean we could see an Austrian India or an Austrian East Indies but at the least it expands Imperial influence in the East and could mean an economic revival for the Southern Netherlands.
A final example is the Holy Roman Empire itself. First, most don't realize that the Empire was actually in a very strong position during the reign of Emperor Josef I and much of the reign of Karl VI. Second, before the rise of Prussia there was no state within the Empire that could challenge Austrian dominance. So, if Friedrich the Great is contained in Brandenburg-Prussia, then there's a remote possibility that the Empire could transform into a federal nation-state on the model of the later German Empire. From my research it seems as though the Empire between the Treaties of Westphalia and Aix-la-Chapelle was slowly heading towards such a thing within the scope of the Imperial constitution. It was only after Friedrich steamrolled over the traditional hierarchy and institutions that the decline truly began and accelerated. Imagine a TTL Emperor Josef II without Prussian opposition. We could see Austria take control of Bavaria, begin to secularize the Ecclesiastical states, create new imperial institutions based on the ones in the Monarchy and much more. But all of this depends on Leopold II inheriting a strong realm than Maria Theresa did.
I would say that this makes a much stronger Austria than OTL. Silesia and the Italian lands should be held. (You never know- but Austria is more likely to retain these things). As for the French alliance, this changes that. The French are historically anti-Habsburg, and the Habsburg Netherlands on their border will be looking nice.
With a POD in 1716 its highly unlikely that the events that necessitated the OTL Diplomatic revolution would still occur. However, that doesn't mean that a reorientation of alliances wouldn't happen eventually. Also, considering that OTL Louis XV returned the Austrian Netherlands after conquering it in its entirety, don't think any TTL conquest would stick.
