@alexmilman is right to suggest that continued pagan Russians would not have had any serious worries about getting 'Crusaded' by Christians until after they had plenty bigger worries about getting Mongol'ed around 1237. And it would be fairly consistent in all the prior years that nomads coming from the east - pechenegs, polovtsy, patzinaks, cumans, would be scarier than any menace incoming from the west up until that time.
But Christian influence had gotten a hold and a lobby within Kiev for a good while before Vladimir committed to conversion.
Svyatoslav tried to remain pagan. Circumstances of his death are a little bit on a mysterious side. During his reign there was already a strong Christian party in Kiev and probably elsewhere. Power of the Russian princes was far from being absolute and chance for this scenario to last is not very good.
There were even some accounts from 100 years before Vladimir of the Kievans being Christian or having many Christians, so you would need to change some internal dynamics in the society.
But, if you did somehow keep the Christian (and Muslim) shares of population (and elite!) low and marginalized and that let retention of a pagan state religion be viable for centuries more, there would be some interesting consequences. There would be lower literacy and no standardized script for Russian, but possibly Orthodox Christians using Cyrillic, some people importing Latin, others Norse Futhark, other Arabic, and maybe a synthetic native script developed.
Presuming paganism lasts through 1237 and the Mongols, by that point it is also after 1204 and Eastern Orthodoxy has lost most of its prestige. So Russia, or southern and eastern parts of it may be as likely to follow Golden Horde leadership in taking Islam and Arabic script as anything. It taking Christianity Russians, or some of them in the west and north would most likely take the Latin version the HRE, Poland, Hungary, and Scandinavia practice, and adopt the Latin script that goes with it.