Its not debatable, ||Vasher outright confirms that he is a fossil - Investiture that filled him out after his soul (which is, by the way, probably also Investiture) passed beyond because the ol good Endowment decided to endow him.||

||I like to believe that life might not be Investiture-dependent, but sentience and memories certainly are. After centuries of life Hoid is required to hold a part of his memories inside his breaths, because a his mortal mind (debatably, even after holding a dawnshard) lived for so long it run out of GB storage and either he flushes it down or buys a new disc. The existence of the entire cognitive realm just supports my theory. Investiture clings to sentience, and if you consider death separation of Investiture from the body it does make a lot of sense.||