Folks talk a lot about SaaS but there are other markets too, like in my case the embedded market. In this market most companies use custom toolchains and proprietary compilers with less-than-ideal standards conformance. The only way for companies to know if my software will even compile with their toolchain is if it's published (open source). That doesn't mean I need to publish all the code; unit tests and project-specific development tools can remain proprietary.

I’d be interested if you elaborated. Open source is definitely a tough starting point, though sometimes it can have some competitive advantages.