Theater vs Cinematograph

It is normal to call screen films a "little brother" compared to the theater. However, this "elder brother" seems to be far behind the theater both under commercial calculations and public opinion. Some claim that the theater is eternal art that "existed, exists, and will always exist".
As it was above said, the screen films didn't have a proper literary foundation at the very beginning. Nevertheless, it emerged very soon having taken literary and dramatic grounds. Therefore, the theater became a cinema competitor and patron at the same time. As soon as film-directors, turned to professional plays and spectacles, the creation of screen films became more money-saving on the one hand, and financially-profitable on the other.
It was Hollywood the first that proposed simplifying the plot stories and adapting literary works for creation of films. It was good because the script writer already had a proper foundation and the product had been well-known by that time. Firstly, screen film directors were supposed to shoot films only on the basis of popular pieces.
Another aspect of theater-cinematograph relation is the fact that the theater is a more elite art genre while cinematograph is a part of Mass Culture. This is the reason why screen films almost turned theater out of Art Olymp in the second part of the 20th century. Complete "death" of theaters that was predicted in the 1950s didn't take place while theater that underwent serious transitional reforms gained even more popularity.
It's obvious that both trends will successfully develop in the 20th century.