The CFM56-7B will remain in production as long as Boeing is still building P-8s. It would cost a not so small fortune to recertify the P-8 with the Leap - too much to be justified for a relatively small production run.
I don't expect to see the NG re-engine with the Leap. The integration of the engine with the airframe makes it cost prohibitive (this is true for most modern airliners).