I've been thinking for some time about when closed source should become open, particularly in the context of when your core business is about producing software. If your core business is to provide a service such as movies, as in the case of Netflix, then the dynamics are different. Because the core business is to produce movies then simply go OSS and reap the benefits from having done so (as Netflix indeed have).
Before I start I should state that my views here don't describe the only reason why to go with open software; there can be other reasons of course. Indeed there are many valid reasons to start with open as well. This post just investigates the closed to open transition, and when to make it.
When your business is about producing software, you're producing software assets that contain costly intellectual property. I'm a massive fan of open software and I've made many contributions in that space. However a software business also needs to make money of course.
I assert that there is a very limited window of opportunity for a software business to retain a software asset as closed; and that window is governed by the open competition that it faces. The job of the software business then, is to stay ahead of the open curve, yet yield to open software when it starts to become a threat. This happened with Java when it was threatened by Apache Harmony. I believe that Harmony subsequently died precisely because of Sun OSS-ing Java.
I should state right now that my thoughts have been influenced by Danese Cooper who gave a great talk on this very subject during Scala Days 2015. Denese discussed why open languages win, and I think her talk has a wider application.
When discussing the subject of open vs closed software with colleagues at Lightbend over the past year or two, I've described closed software as resting on a tectonic plates. As these plates move around then the closed software at the edge falls off into the abyss of open software! I think that the analogy is mostly useful though in order to illustrate that the world changes. Because of this if you must regularly re-evaluate the competition that is open. If you have closed software solving a particularly useful/important problem then you can be fairly certain that open software will rise around it (again thinking of what Denese said here).
Open your commercial software and neutralise its open competition, also reaping the benefits of having gone open. Focus on adding higher level value building out from your core. Stay ahead of the game.
You certainly can't sit still.