I think the Reds think Mike Leake is going to be their change of pace guy in between the bigger arms.
If Leake doesn't have a decent season next year, though, they might look at offering Arroyo a one year deal. How Corcino and Cingrani develop will probably effect the decisions as well. Chapman should stay the dominant closer for the rest of his time with the Reds in my opinion.
If evolution is outlawed, only outlaws will evolve!