I work on Enterprise projects and we almost always buy support contracts, for both paid-license and open-source software, if they are available; you don't need creative licensing models to get enterprise to pay for open source software, you just need to provide an opportunity to pay to have a live person respond to and manage issues for enterprise customers.
Enterprise companies also don't like to run "unsupported" software. So there is definitely an opportunity here.
If there is an opportunity here, it's most likely in collective effort. An open source guild/union could provide a support pool/cohort of contributors to cover 24/7/365 or what have you support agreements, an insurance pool for SLA guarantees broken/fees, broker and collectively bargain with enterprises for support contracts that cover costs and wages for entire direct and indirect dependency chains, rather than just obvious direct dependencies or splashy well branded dependencies.
1. Do open source maintainers actually want to commit to that?
2. What if the response is "Yes, we don't support that and don't plan to?" and the company feels this doesn't qualify as enough support and causes a headache.
3. If the purchaser knows what they're getting into, what's to say their successor also does?
It is simply not possible for us to add a "donation" cost to our projects. That will not get past accounting.
A license, on the other hand, we would have no issues purchasing that.
We purchase (expensive) licenses to proprietary software all the time. We could and would do the same for the open source software, we use, but without being able to purchase a license, there really isn't any practical way of doing that.
Free for everyone, except for enterprise production environments, would work for us. As long as we get a license key and an invoice.