That also means Silesia is seized by Poland along with Habsburg Hungary, both Silesia and Galicia are important land connections to Hungary..I see it could happen if the Polish Jagiellons step in and save Hungary. The Commonwealth could manage to defeat Muscovy and retain dominance of Eastern Europe. Maybe even a crusade against the Turks, though that could be too wankish...
What if Poland, Lithuania, and Hungary were unified in a commonwealth as Poland and Lithuania were IOTL? A vast realm with simultaneous Baltic, Black, and Adriatic coasts would be hugely powerful.