User blog comment:Doctor261/Polish-Lithuanian Victory?/@comment-32656-20120709024645

...They managed all of those, more or less, otl. It's the Russians they should have worried about.

That being said, the only way it can survive is to remove the electoral aspect of their monarchy. While some nations made it work, all it did was make them into a game for other nations. Recognizing the Slavs would have went a long way, too.