Do you think his "redemption" helped save/extend his life?
None of the future scenes where Scrooge had died look like they're much further in the future, and he didn't really seem old enough to be a few years away from death. When the peddler was selling his stuff, they seemed to think he died from an illness rather than old age.
Maybe within a few years of the "present", he got horribly ill. But as he build bridges with the Cratchitt's, they helped nurse him back to health, and sought out medical health Scrooge was too ill to seek himself, and/or too tight to pay for lol.
So the Ghosts' visit saved both Scrooge and Tim!