As much as I hate to agree with you....Slavs will NEVER be majority Muslim. The few freaks who are will die out or be expunged. And if it even looked like it was happing....they would have a pogram the likes you never seen.
Already happened .If you check the history of cherkessia ,you will realise the russian saw them as brothers and fellow slavs 500 years ago .At that time cherkess were pagan or christian.Almost no wars with cherkessia.The moment majority cherkess converted to islam in 18-19th century ,the tsars started the genocidal invasion of cherkessia and banished its people ,specially those who refused to convert back to christianity.