This is why PostgreSQL is awesome. You can freely mix relational with non-relational (object) storage depending on your needs.
This is only if you ignore why people moved to NoSQL in the first place. PgSQL is great for a lot of things, but I would argue that if you're using it you're betting on your overall product/service having some other killer advantage than data processing. The competent wing of the NoSQL crowd are using it in strange ways that enable new classes of product and service that cannot be achieved with PgSQL.
Though your last line makes me curious. What is an example of one of these new classes of product and service that can't be achieved with PgSQL?