The Cliff House was closed during much of the 1920s and '30s until George Whitney bought it in 1937. I imagine that the building is structurally sound after the extensive remodeling a few years ago, so something will open there when times get better. Whether or not it will be called the Cliff House is uncertain.
I hadn't eaten there in about 30 years, the last time being when I hosted a guest from Canada. It's always seemed strictly for tourists to me, though it was just great knowing that it remained as a SF landmark.