Yes, there might be. The Naruto and Blue Exorcist fandoms are both quite large, and it's not uncommon for fans to create crossover fanfictions. You can try searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own.
Naruto's chakra-based powers could potentially enhance the exorcist powers. For example, his Rasengan, which is a concentrated form of chakra, might be able to disrupt a demon's energy in a way that normal exorcist attacks can't. His shadow clone jutsu could also be used for reconnaissance in the world of Blue Exorcist, helping the exorcists plan their attacks better.
It could be about Naruto somehow ending up in the world of Blue Exorcist and taking on the role or having the abilities of Rin. Maybe he has to fight demons in the Blue Exorcist style while still having his Naruto - like skills.
One idea could be a crossover where Naruto characters end up in the world of Blue Exorcist. For example, Naruto and his friends could be mistaken for exorcists and get involved in battles against demons. Another idea is to create an alternate universe where the main characters of Blue Exorcist have the powers of Naruto characters. Maybe Rin could have the Nine - Tails' chakra and have to learn to control it like Naruto did.
Yes, the Blue Exorcist manga is over. It took readers on an exciting journey and concluded in a way that left a lasting impression. The final chapters brought closure to the characters and their adventures.