I think Quinn's feelings towards MC have two phases:
-First one, MC is Quinn's fantasy. She knows he's (or will be when he passes the "freshy" phase) the kind of guy she likes, and somehow dreams with being a "normal" girl, like Sage or Jill, for example. A girl with a life way less complicated, and being able to just date a guy like MC and be happy. That's what she asks to the "8-ball" when she's at MC's room. We know the answer. But during the hang out in Quinn's room, she waits until he's asleep to cuddle with him. She knows its not real, but she wants to play just for a moment at being a normal girl with a normal boyfriend to cuddle with. But probably she doesn't think in MC as a real partner possibility there. After the scene in the park in front of the library, the idea just begins to appear in her brain, specially because she sees MC is interested in her even after knowing her a little bit. I suppose most of the guys she knows including the DIKs are aware that they couldn't handle her, and maintain the distances. MC in Quinn's path is different.
-Second one, after Vinnie's visit to MC' room, Quinn realizes that because of her activities, Vinnie came to the party and now MC is into Vinnie's radar. He's in danger somehow because of her and Tommy. So she decides to involve him in her business as a mean of not keeping him in the ignorance and keep an eye on him. Now, if he's involved at least in some of Quinn's business, there could be a real possibility of some kind of relationship between MC and her in Quinn's brain. Not that Quinn is decided to seriously date MC or something like that, she's not that kind of girl, but at least something like "rolling together", as Lily would say.
I don't think MC is going to be a second Vinnie. I suppose Vinnie was more than ready to be introduced into the drugs world, and I don't think MC is that kind of guy. But somehow he's going to be involved, and probably is going to at least try to "rescue" Quinn of that life. Probably at some point Vinnie is going to try to physically harm Quinn in retaliation of stealing his territory, and MC is going to have a serious fight with him to protect her, although I don't think that is going to happen in the next episode. Maybe is going to be the ending of the season 3 or something like that. I see MC in a hospital with a bullet wound, but not as a drug dealer.