Sarah is most likely the cardinal who hails from Guinea, and is the ultra-conservative prefect of the congregation for Divine Worship and Discipline of the Sacraments.  He has publicly favored the ad orientem aspect of the Tridentine/Extraordinary form of the Mass, to Pope Francis' dismay.  At age 71, Sarah could likely hold that position for another four years, until he turns 75.  (Burke is three years younger than Sarah.  I am hoping that neither of these cardinals ever becomes pope.