If your product or service relies on an open source project, ensuring the sustainability of that project is just good business sense. Forking that source project should be a last resort, to be considered only after all other options have been exhausted. But writing a detailed plan to fork has two benefits. First, it ensures that should the worst happen, you’ve already considered how you’ll deal with it. But perhaps more importantly, thinking proactively about forking will help you take actions that will ensure that it never gets to that.