NBC's The Voice has become the latest TV talent show to revamp its celebrity panel. But, it indicated on Monday, the addition of pop stars Usher and Shakira is only temporary and that Christina Aguilera and CeeLo Green will return for the fifth season of the singing competition. Aguilera, the network said, is being given time off so that she can embark on a concert tour to promote her latest album and Green is reportedly working on a new album as well as a sitcom based on his life. Doing two back-to-back cycles of this show requires a tremendous amount of time, and we are happy to accommodate the commitments made by Christina and CeeLo, said NBC Entertainment chairman Bob Greenblatt in a statement. The participants on our show benefit from our coaches' expertise and their continued success in the music business allows for significant new contributions to the contestants when they return.