Apparently, Emperor Charles VI's death in October 1740 was quite unexpected, and probably brought on by accidentally eating poisonous mushrooms. As we know, that death brought on the War of the Austrian Succession, which set the terms for European politics for the next several decades, in particular being responsible for bringing Prussia to prominence through Frederick the Great's seizure of Silesia.
So: what if Charles manages to hang on for ten more years?
A few thoughts:
1) the Austrian army was in a very bad state in 1740, having just finished a rather embarrassing and unsuccessful war against the Ottoman Empire the year before. A few more years of peace would have been very helpful.
2) Britain and Spain are already at war in October 1740, and the French are considering joining the Spanish. It seems to doubtful that this war would be more than desultory, but an independent, non-continental war of this sort might have interesting consequences.
3) The big territorial claim that had always obsessed Frederick William I was the Jülich-Berg inheritance. Prussia had had a claim to these territories since the original Jülich succession crisis of 1609, and the then current ruler, the Elector Palatine Karl III Philipp, had no sons. Most of the powers, and I believe the Imperial Diet, had agreed that Karl Philipp's heir in the Palatinate, Karl Theodor of Sulzbach, should also inherit Jülich and Berg, and this was to be cemented in 1742 by Karl Theodor's marriage to his cousin Elisabeth Auguste, Karl Philipp's granddaughter. But Frederick William strongly disagreed.
Karl Philipp died in December 1742 OTL, and likely would here as well. OTL, Frederick wasn't super interested, as he obviously had bigger things on his plate. But here, this seems like it would almost certainly merit some sort of Prussian response, right?
4) I know the shenanigans in Russia following the death of Empress Anna were tightly connected to the politics of what was going on in Western Europe. The Regent Anna Leopoldovna was pro-Austrian, and Grand Duchess Elizabeth's coup was supported by the French and Swedes on account of that. So presumably there's some effects here.
5) Charles Albert of Bavaria, OTL's Emperor Charles VII, died in 1745. His health might have been adversely affected by the troubles of his later years, but it seems unlikely he'd live to 1750. What then happens to his claim to the imperial throne when Charles VI does die? Does his son Maximilian Joseph put himself forward? OTL Max was not nearly so ambitious as his father.
6) Cardinal Fleury was still running French policy in 1740 OTL, but was losing influence to younger, more bellicose types like Marshal Belle-Isle. Fleury is surely dead by 1750 - who's running French at that point? Would they pursue a policy as ambitious as Belle-Isle did OTL?
7) Similarly, Walpole is going to be out of power and dead by 1750. Who's in charge, though? Carteret? The Pelhams? What kind of attitude will they take?
8) Philip V of Spain died in 1746. His successor, Ferdinand VI, his son by his first wife, was utterly uninterested in going to war with Austria in order to find Italian principalities for his half-brothers.
Do we get a general war in Europe at any point here, either as a result of the Anglo-Spanish War, the Jülich-Berg succession, or Charles's later death?