The rally in municipal bonds has more to run, but future returns will likely come more from income rather than price appreciation as rates rise, said Sean Carney, Municipal Bond Strategist for BlackRock. Carney said municipalities are generally still healthy and have not increased their debt issuance, creating a favorable supply environment. He added that issuance generally rises in the fall but it should not be so overwhelming as to dampen prices. Carney also said that Detroit and Puerto Rico are outliers, and potential problems in other high profile areas are well known by investors because they are pension related.