tinfoil said:What about having Gustavus Adolphus survive Lutzen in 1632 and going on to found an empire as you described? One could easily resolve a '31 years war' where he is successful in poland/lithuania but then loses central brandenburg/saxony/etc to a hapsburg/french coalition.
I don't see Gustavus Adolphus being elected King of the Commonwealth over Wladyslaws, he is not decended from the Jagiellonions. That does not mean he won't be a player in the Union. Make him Duke of Livonia for instance to bring the Protestants there under a Protestant Duke but still owing his feudal alliegiances to Wladyslaws and at the same time it transfers it nominally into the Swedish sphere. It should engender more support among the Protestants when the conflict with the Ottomans surfaces. In this TL the Vasas may not want to be so overtly allied with the Habsburgs, but without any problems from Sweden to deal with, then the resources of the Commonwealth can be put to more effective use when the Magnates War occurs. Sigismund and Wladyslaws and the Habsburgs may very well be at odds over the disposition of Transylvania,Wallachia and Moldavia.
Wladyslaws himself may even marry a Protestant this TL absent absent any serious trouble from the Swedes or the Polish Protestant nobility. He requested permission from the Pope OTL but was given what he thought was a blunt and rude refusal. Absent the need for a serious alliance with the Habsburgs and a stronger Protestant influence he may just go ahead and do it. The leading contender would be Elizabeth of Bohemia, daughter of the Winter King of Bohemia. If the Pope decides to excommunicate him he will gain wide spread support among his Protestant subjects and will almost certainly stop the counter-reformation in its tracks in Poland.