The use of Open Source software has never been more widespread and accepted before. Virtually every software company in existence now use Open Source in products and infrastructure. Open Source is easy to use and the modern way to make software reusable. It does not die and vanish when individual products or companies fade away.
Open Source has penetrated every aspect of the software industry and there is no longer any areas that are considered "too important" to let Open Source in. That includes defense systems, airplanes and interplanetary space missions.