When I first joined the church we sustained the Patriarch of the Church, along with the First Presidency and the Quorum of the Twelve as a "Prophet, Seer and Revelator." I would expect that at some point Patriarch Smith will be succeeded by his oldest, direct, descendant, unless there is still a living sibling of his upon whom the office would devolve (which I doubt).
When the office was established, it formed an independent line of priesthood authority. This line was not be dependent upon selection by temporary office holders drawn from many family lines. Instead the Smith family, through whom the church was restored, would hold this hereditary office forever. It will be interesting to see how this office is handled in the future.
