There are already tons of source available models that tons of companies use. Nothing is stopping you from putting your code on Github right now with a proprietary license. Of course, even in that scenario most users prefer single-time purchases to subscription models.
If you want to go off and develop a new proprietary subscription license, then fine. But don't market it as a solution to OSS problems, that's deceptive.
> All of your suggestions ultimately boil down to altruism by commercial entities
Quite literally none of my suggestions boil down to that, I deliberately left donations off the list. In every single model a commercial entity pays for something they would not be able to get for free: advertising, permission to bypass GPL infection of their own code, support and access to developers, new features, or an enhanced proprietary version.
I'd suggest not to use the term when promoting your idea, it's kind of misleading and will provoke such discussion every time.
I don’t think this statement is accurate as there are decades old projects (linux/gnu, apache) to dispute your claim. I think this is possible because software actually is possible where a few individuals can have great reach with part time or employer funded time. And also because companies can benefit by funding and releasing activities that aren’t core to their business as either advertising or inclination by developers to be altruistic or other reasons (MSCode, Google stuff, etc).
Giving away your work for one and all to come and take is, ultimately, unsustainable. All of your suggestions ultimately boil down to altruism by commercial entities, and that's also not sustainable. Companies care about legal compliance but don't want to contract with a million little entities to comply. That's why FOSS is so popular for companies and so terrible for maintainers. Companies get to build their business on this great software and completely ignore the externalities that it takes to get there.
If there were one central organization (or heck, a handful) where companies could register and pay for one license that entitles them to use any software licensed by that organization I think we would be far better off as a community.