[Jon]

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.

Not sure that was really an issue because it lasted many years with the winner becoming a massive star very few years. Even as far back as Pop Idol 2 the winner failed to achieve anything outside perhaps their first single or two most years. 

Had it have continued to get 7 or 8 million viewers it would have still been on air. I think people just got bored of the format and constant changes, as well as suffering from younger viewers slowly moving away from traditional TV viewing.

Strictly on the other hand always skewed older and any changes to the format happening slowly over the years.