The development of closed-source software will continue. It may be undesirable for the source of a homegrown business system to be open, because it reveals so much about the business's procedures and capabilities. A company may want to keep the source of its business systems confidential. Many applications are developed only when someone believes they can make money renting them. While the benefits of open source are becoming more widely appreciated, closed-source software will continue to be developed.
Applications generally make use of pre-existing software components.
Almost all programs use general-purpose function libraries that come with compilers. Many applications provide a front end using a GUI framework that comes with the compiler or a third party. Some software uses special-purpose libraries to do things like statistical analysis or mapping projections. There is less risk in using a third-party component if it is open source. This is particularly true of components developed by small companies and individual developers.