While anything is possible I think that a Mikhail based light novel is unlikely. If there is to be character development for him it would first need to take place in the manga for the sake of continuity. If the story continues on long enough perhaps it could happen down the road but in the meantime there is always Mikhail fanfic. :)
I'm not saying that it should be necessarily about and only Mikhail. It could have some storylines combined like: Mikhail, The Russians rebels, the origin of the scars, relationship with Baishe, Baishe's leadership (Tao maybe). Is there's something Mikhail might got to know is who truly Tao is. Between the moment Yan abuses Fei and escapes and Yoh finds and kills him there's enough time for Yan to tell that inconvenient truth to others.
Guys and ladies, do you think Sensei and Satoko Ai will create another Finder novel (maybe with Mikhail this time)?. I have this idea because they tend to do it for the side stories or for the side characters. I think there's enough material to create many interesting storylines. What's your opinion?