If a quant outsider constructs a very influential model, I could see that ending up in a Nobel, especially if it goes through a conventional publication process. I think though quants are generally kept very busy with non-academic things.

For finance in particular, my impression is that quants that make good discoveries keep them to themselves, because that's how they make money! After a while, some academic notices the same thing, formalizes it, and then publishes, and then the opportunity is gone.