Ancestry is warning that some English surnames are in danger of dying out. They compared names in the 1901 census with more recent records and found names like Hatman, Rummage (love that one) and Temples no longer exist. It says that names like Clegg and Greenwood are dwindling and one day could die out too.
But this is a process that has happened for centuries, names die out and names are also created. Some time ago i found a website (which unfortunately no longer seems active) that could let you map where a surname was common in the British Isles over time. I tracked one of my ancestral names (on my old blog) Genner between 1881 and 1998 to see how the distribution of the Genners changed over time.