1772 Prussia, Austria, and Russia invaded congress poland with the intention of dividing it up between themselves. Most of the world was sure that Poland was doomed as a country. Instead thanks to various acts of incompetance, a few cases of bad weather, and in the case of Prussia rash of disease that killed Fredrick the great, and of course the bravery and skill of the polish army the alliance was defeated.
Poland exited the war bloodied but they remained intact, the war of triple alliance would go down as their finest moment, Poland for all of its issues would continue to exist to the present day, but the war was at times a near thing. What would the world be like if Poland had lost?
Even if the Polish armies were defeated in 1772, I don't believe that Austria, Prussia and Russia will be able to divided the country just after one war, it will take more time to do it. Probably a first partition in 1772, then the Three Black Eagle will set up a puppet regime in Warsaw, and they will fought about influence in this new governement. Probably the three of them could fight between them for who will have more of influence on the Poles, or more of PLC territories during a second partition.
In OTL, the Triple Alliance represent a powerful ennemy to revolutionnary France, when both Austria and Prussia send powerful armies against France in 1792, while Russia protected their borders from Poland and the Ottoman Empire... Austria don't need to protect its eastern and southern border because the Cossacks were doing it, so Austria were able to send more troops to southern France or northern Italy.
Remember that one of the most important reason for russian troops to be unable to crush polish and lituanian armies in the east of the PLC was that at the same time, the Russians were fighting the Ottomans and the Crimean Khanate, it was the Russo-Turkish War of 1768-1775. When the peace was signed, the Russian obtained that both the Wallachian and Moldavian principalities became theirs and it was by this road that russian armies could help Austrian in northern Italy and Swiss to fight against the French. Seems that the Ottoman payed dearly for their support of Poland during the War of Triple Alliance...
Would Eastern-Central Europe and Scandinavia have been spared the scourge of Communionism as set up by the PLC revolution following the Depression?
Would Russia have retreated into Nationalism as OTL?
Would the Scandinavian Royal families have merged while in exile in Iceland (under UK protection) and formed the Royal Scandinavian Federation?
Lots of questions!
One of the aggravating fact of the PLC Revolution was that it was not only a social revolution but the ethnic diversities of both Poland and Hunagry played against them. In Poland, it begun as a revolution of the poor ruthenian peasants against polish middle and high class, and of course against the Jews, sometimes it was as bad and bloody as the Cossacks revolts in the XVIIth century when the Cossacks and the Ruthenian peasants slaughtered alike Polish Szlachta, catholics priests and jewish shopkeepers. It was the same in Hungary, but you replaced the Ruthenian by the Slovaks and the Rumanians...
If Poland was partitioned and didn't existed during the Revolution, a similar fate could happen to Austria or Russia, if these countries were able to keep their multi-ethnic Empire, socially diverse.
The French and American Revolutions wouldn't have gone on unimpeded. Poland being Revolutionnary France's best Continental ally, I could see Poland being recreated for a while by Nappy, but still losing in the end. Perhaps not in Finland, perhaps Russia ?
Well Poland was shocked as much as Europe by the execution of Louis XVI and all the bloody events of the French Revolution. And I don't think you can called PLC, the best ally of Revolutionnary France because the PLC was simply neutral. Later, they were allies but only because Russia gave the Poles an ultimatum about the free travel of russian troops throw PLC territories to save prussian territories from french invasion.
Apart from the partition of Prussia which was reduced to only the Brandenburg, the Revolution in France had another good consequences as the PLC Szlachta realized that the Reformists are right about given more power to the townfolk before they tried something similar to the French Bourgeois revolution. And such they signed the 1794 Constitution. It was the first step to many economic and social reforms in Poland... The Poles reacted the same way after the Saint Barthelemy Massacre in 1572 when in 1573, The Warsaw Confederation extended religious tolerance to nobility and free persons within the PLC.