<p>This paper introduces a novel reverse replacement thought experiment to reassess the metaphysical foundations of mind-uploading optimism. While gradual replacement uploading is often considered the most promising strategy for preserving consciousness and personal identity, my analysis reveals profound tensions underlying this view. By exploring the gradual substitution of a silicon-based system with biological neurons, I argue that preservation of functional organization cannot guarantee the continuity of consciousness or personal identity. If functionalism is maintained, multiplicity becomes unavoidable, undermining the meaningfulness of survival. Conversely, if uniqueness of identity is prioritized, the functionalist assumptions that originally motivated uploading optimism should be abandoned. The reverse replacement scenario thus forces a philosophical dilemma: either accept the radical fragmentation of personal identity or reframe the criteria for survival beyond functional organization. I conclude that mind-uploading theories must confront deeper metaphysical challenges than previously recognized, requiring a reconsideration of the relationships among consciousness, personal identity, and functionalism.</p>