[tellyblues]

Evolution, not revolution seems to be the name of the game to keep formats running rather than crashing and burning. Look at GMB's longevity versus it's predecessor's (or the aforementioned X factor vs BGT).

The X Factor was always going to end because it had the off-air element of making someone a star which couldn't be sustained. All BGT has to do is send someone to the Royal Variety Performance each year. The shine of winning Strictly isn't in danger of disappearing because contestants don't have to do any more at that point. It's also far more difficult to keep a singing show fresh compared to a variety show or even dancing because you're limited with music.