By that point there will be enough digitized entertainment already produced to last a lifetime. We’re just on the long tail of diminishing returns now.
By that point? There already is and has been for years. Many more life times worth of movies and shows than any one person could ever hope to watch.
If we're going just off of the total runtime of all films ever produced, that point was probably already reached before WW2. But that's not entirely relevant, because an average person won't be equally interested in watching everything. There could still be increasingly small niches to fill.