My impression is that Hibernate is the most widely used implementation of JPA (before OpenJPA and EclipseLink), and also that its native API is still more powerful than JPA 2. For those reasons alone I think it will be around for good long time.
I agree. Hibernate is like a superset of JPA. (and has Hibernate Core if you want to follow the spec verbatim.) JPA is catching up to where Hibernate was. Hibernate is still ahead. It's a moving target.