He was a talented general, but he had his flaws. Aside from his failing mental faculties at the end of his life, he wasn't that great of a logistician, so sometimes they failed to follow up on a tactical victory in the War of Spanish Succession since pursuit would have put them at risk of starvation. Also, he left no plan for his successor, something that would cause problems in the War of Austrian Succession. The idea of providing garrison troops adequate field battle training never seemed to have occurred to him, so when they were used as an ad hoc field army in the War of Polish Succession and Austrian Succession, they were little more green troops with some idea on infantry vs infantry fights, but no idea how to deal with cavalry other than "yeah, form a square we never practiced for before"
Actually, I wonder why squares were the anti cavalry formation. It really should be a hexagon, which is a bit harder to drill for, but would be slightly more effective against cavalry and considerably more against combined infantry and cavalry assault.
OK, let's try to get some concrete events. You can take these into your timeline or not let's just say it's a possibility.
In the battle of Mollwitz in 1741, Prince Eugene expects his larger forces to win, but due to poor drilling, bad reconnaissance, and pre committing his cavalry reserve when the right wing shattered to a cavalry charge causes them to lose control of the battle. Eugene of Savoy extracts his forces safely without much loses. By May 1741, he fortifies Striegau and prepares for the Prussian assault. 32 Thousand Prussians attack, but this time Eugene is ready. He marshals 3000 cavalry into three separate groups and each group slams into the Prussian left flank. The artillery fires 4 volleys into the Prussian front, and the Austrian infantry counterattacks. in the actual fighting the Austrians lose 3420 troops and the Prussians lose 8930. In the end, 3K Prussian prisoners are captured as they try to flee in vain, while artillery and siege train is also captured. Despite the losses of battle, the Prussians don't lose heart. This time their King Frederick stayed with them the whole battle unlike in Mollwitz. The Austrians advance, but eventually they start wandering off. They sack and loot the 4th, 6th, and 7th largest urban areas of Prussia before falling back for the winter. Prussia and Austria agree to a 38 month truce.
In 1942, Eugene is sent to help Otto Ferdinand Graf von Traun on the Italian front. They face 40,000 Spanish and Nepalitians. The previous year, just like real life, the von Traun forces the Modena duke to cave to Austria without a fight. While the enemy is in disorder, the Austrian armies launch a surprise attack in September of 1741, inflicting 3,000 casualties while suffering a third of that. This unerves the Spanish enough to not take offensive operations until reinforcements arrive in 1743.
Eugene is once again transferred, von Traun is seen as a capable leader, probably able to hold the Po Valley on his own. The Prussians are in a truce and most defiantly will not break a truce *cough.* The fronts in Bavaria and Netherlands need leadership. In 1743 The French launch an attack into Austrian Netherlands with 62,000 troops, reasoning that their losses at Dettingen can be compensated if they can capture some channel ports. The Pragmatic Army failed to capitalize at Dettingen, but Prince Eugene convinces them that they can have another field victory. 3,000 Hannoverians, 10,000 British, and 45,000 Austrians head West tot he Netherlands. By luck, some of the Austrian Dragoons spot the French trying to attack Ghent and its outdated fortifications. The Pragmatic Army soon cuts off the French from their supply lines. The French, still in disorder after Dettingen, attack blindly at the Pragmatic Army's improvised fortifications. The Austrians advance in oblique order, concentrating on their right flank and smashing the French. Some of the French decide rather than trying to fight the Austrians, they flee into the East forested area around Ghent where the British patrols are sporadic and pursuit is difficult. The Austrians and British dismissed heavily investing this area as it cannot be sued to flank the main army. The Austrians take 34,000 prisoners, while the rest of the French army escapes with light arms through there.
Prince Eugene asks for 90 days of rest, he is getting physically and mentally tired. Austria keeps him deployed there for the next year, while the British take de facto command. Unfortunately, they are too slow to react to anything, just like real life, so nothing happens for the moment.
Of being able to field 300,000 troops at multiple fronts in the Seven years War later means the material losses to France isn't even that much.
What do you think? I can imagine the Prince in his Prime being able to pull those off (and maaaaybe when he's old). Winning the War of Austrian Succession with less losses means they would be able to take on the Turks more easily.