I was arguing with someone who had decided to make a Wikipedia page for "12 inches" and wanted it to be separate from "foot".
him: "I'm concerned about people making links to 'a foot' expecting it to be 12 inches, and then someone changes the definition."
me: "The number of problems that would be caused by this were much grander than the Wikipedia page. If it ever happens, what we'll do is change the artile for 'a foot' to be a disambiguation page for the '12-inch foot' and the '13 inch foot'."
him: "Well, changing the definition has been considered before. So this is a very real scenario."