Mima this, and Mima that. When are we gonna start hearing about Rika and Shinki, huh?!
But, I really don't think this story-line is a reason for Mima to come back. Sure, she's a spirit, sure, she haunts the Hakurei Shrine, but she's an Evil Spirit/Ghost/Extended Metaphor for why pointy hats are cool. This game is about divine spirits so I really don't think ZUN would even think of getting Mima involved.