How viable is the business model charging for the privilege of running your code? Like someone else mentioned, I think it's the wrong question. "Closed source"

How viable is the business model charging for the privilege of running your code? Like someone else mentioned, I think it's the wrong question. "Closed source" in many applications is moving towards SaaS aka subscription based where what you're paying for is an always update version that is available wherever. The value is derived from the delivery model, not from hiding the source code. I would probably still pay for e.g. office 365 if it was open source because the value doesn't come from the source code. If I'm looking for a scripting language, I can't imagine paying for the privilege of using it cough Matlab. I think to a large extent, acess to the source is irrelevant to the business model, as it's not where the value comes from.