see mulim parts of Russia to imagine what a all-muslim Russia would be like
basically it would look a lot like Chechenia and Kazahstan olnly bigger, peacefull and prosperous
other than the huge butterflie effect on mideval european politics and strategy, id say the realy big changes would start with the 17to19th century, as this muslim Russia would at the same time be part of european culture, but also completely integrated in muslim culture with arab alfabet and language
this would change a huge deal in terms of formation of cultural and political blocks, especialy seeing the influence of Russia in OTL azia
also Islam would no doubt sperad to practically all of Azia
olnly thing is theres no way this can happen as the cronicles clearly state the Rus considered Islam, but decided they just cant give up pork and votka