I think the implied argument is "you can't safely assume that any market niche will be filled when the big player(s) go away, sometimes the niche just stays empty"
Camera sales, which are overwhelming which is overwhelmingly digital cameras, fell 93% from 2010 to 2021. In 2022 8 million digital cameras with a value of $5 billion were shipped.
Based upon those numbers I would say digital cameras are a niche and no longer one of the most popular consumer products.