He and his wife live at Castle McDuck, which - due to magic druid stones - has turned magic and granted them immortality. However, it has also closed off the castle from the rest of the world, except for once every five years, when it becomes accessible from the rest of the world.
On Webby’s board, in "Woo-oo!", there is a note saying "Scotty McDuck → Alternate Timeline????". This is a reference to personal notes made by Carl Barks, naming Scrooge's father "Old 'Scotty' McDuck".