First, after seeing Novgorod repel the teutonic knights, the duke of Lithuania sees them as an equally potent ally to Lithuania as Poland, and seeing as a unification with them would make more sense culturally (since following the unification into the polish-lithuanian commonwealth lead to the Polonization of much of Lithuania, and East Slavic culture wasn't in as strong a state of development as Polish culture) the GDL converts to eastern orthodoxy and fuses with Novgorod instead of Poland via royalty marrying royalty. Then, Novgorod-Lithuania & Moscow assist the Tver uprising instead of helping the Mongols, and agree to also fuse via royalty marrying royalty. Then, the Russians forge a defensive pact with the Eastern orthodox states in the Caucasus like Alania, Circassia & the Kingdom of Georgia. Would the Golden horde just reconquer them? I doubt it as they had a huge earthquake around this time and they'd have the Timurids to deal with soon after.