This does aggravate some of the OSS community, however. Calls of "Google is taking over C++" or "Embrace, Extend, Extinguish" are common from the community. This represents a big problem: the community does not agree about what future they want to build.
But, anyway, since anyone can use open source for free, what are open source maintainers going to be invoicing and getting paid for? It seems to me it's not going to be maintaining the software itself -- since you can use the maintained software without paying, anything you pay for maintenance is effectively just a voluntary donation, not a straightforward invoice for work.
So whatever you're invoicing for and getting people to pay is... something other than maintaining the open source software. It seems to me that is not solving the problem of "how do you get maintainers paid", in fact it's taking the people who are well-placed to be maintainers and reallocating their time somewhere else to something they can get paid for, and hoping there's enough net profit they can keep maintaining in their unbilled hours just because they feel like it.
The OP's perspective is more: "How do we get maintainers paid for maintaining? If you are a company with budget who wants to, here's how. If you instead pay someone for doing something other than maintaining, which is often what people end up doing (paying for features or what have you)... that does not actually make maintaining pay, it doesn't work to make maintaining pay."
In practice I suspect we'll see a lot more license changes and hostage source in the future.
I guess it's a way of making a voluntary regular donation seem like a traditional invoice to satisfy the bookkeepers, but that's not what I thought @mfer was getting at. And if it magically worked to produce what are effectively donations, we probably wouldn't be having this conversation. "
But yes, you are talking about something other than open source as the more likely future route, which is why i asked @mfer if they were! That's the straightforward way to get people to pay for software -- make it not open source, so they have to pay to use it.
Donations don't work. Even recurring ones. Large companies have legal hurdles in paying that way. The legal hurdles are very large and are legal ones. Things they don't control.
A long tradition has existing among some of setting up a business, having invoices, and providing services for the pay (e.g., some consulting, logo on the site (marketing), etc).
Setting up a business and handling this this way is how other industries have long worked. I think of my local electrician. It's not hard.
Just an idea of how to turn an idea into a practical reality.