If King Charles III passes away before Queen Camilla, her official title would likely change from "Queen Consort" to "Queen Dowager." This is the traditional term for the widow of a King. Because she does not share the King's sovereignty or hereditary claim to the throne, she would not remain the reigning Queen. Instead, the throne would immediately pass to the next in line, currently Prince William, and Catherine (Kate Middleton) would become the new Queen Consort. As Queen Dowager, Camilla would retain her high social status and likely continue her charitable work and public patronages, but she would no longer be the most senior female member of the Royal Family. Regarding her residence, while she might stay in a royal apartment or home such as Clarence House, the primary royal residences like Buckingham Palace would be occupied by the new King. She would remain well-supported by the Crown through the "Civil List" or the Sovereign Grant, ensuring her security and staff are maintained for life.