After the Baltic Crusades, there were several attempts from the native balts of recovering their independence. The most successful of these was the Great Prussian Rebellion, Which even had Mindaugas support (but finally was crushed, as the first Lithuanian king was murdered).
So, suppose that Mindaugas is not killed by his nephew, constantly sends military support to his fellow Prussians, crushing the Teutonic fortress at Konigsberg and finally destroying the monastic state of Prussia.
What would be the main effects on European history? without a significant Teutonic threat, would the Lithuanians convert to Catholicism?