George Q. Cannon teaches being sealed up to eternal life is conditional.
George Q. Cannon, "The Latter-day Saints Aspire to Celestial Glory," in Journal of Discourses, 26 vols. (Liverpool: John Henry Smith, 1884), 24:274
When he sealed a man up to eternal life, he bestowed upon him the blessings pertaining to eternity, and to the Godhead, or when he delegated others to do it in his stead, God in the eternal world recorded the act; the blessings that were sealed upon that man or that woman, they were sealed to be binding in this life, and in that life which is to come; they became part of the records of eternity, and would be fulfilled to the very letter upon the heads of those upon whom they were pronounced, provided they were faithful before God, and fulfilled their part of the covenant. There is no doubt about it.