The traditional date given for the introduction of Christianity to Poland is 966, when Mieszko I was baptized into Latin Rite Christianity. However, there is evidence that the Slavic Rite (of Sts. Cyril and Methodius) had already been introduced to Poland prior to that year, and that Mieszko's conversion was not from paganism but from Slavonic to Latin Christianity.
So this thread asks to assume that that theory is correct, that Slavonic Christianity was present in Poland prior to 966, and posits that the Piasts hold onto it rather than adopting the Latin liturgy. What happens then? How does this impact relations with Bohemia and the HRE? With Rus?
And when the Great Schism starts up in the following century, which side will Slavonic Poland pick? Communion with Rome despite the different liturgy (like the OTL Byzantine Catholics) or communion with Constantinople? Or will Poland simply find itself overrun by German crusaders until it conforms to the Latin rite?