Perhaps a better question is: “How often do brands change?” Because the answer to the original question is: “Of course they do.”
Brands change all the time. They evolve (even religion-related brands). Sometimes they reach out to new markets. Sometimes they extend their brand families to include new products. Sometimes they pare back. The key for brands that are in some type of transition is to make sure they can still tell an authentic brand story that reflects their earlier stories.
This doesn’t mean that a brand can’t evolve and become something entirely new. It doesn’t even preclude complete revolution. When America declared its independence, it stated a new brand story. And it started by using the old brand story for counterpoint.
So if you’re thinking about changing your brand — go for it. Just make sure you figure out how your old brand story is related to your new brand story.