> First of all, the usual suspects who rip off high quality open source projects have been known to just create a fork if the license changes (see Amazon and Elasticsearch).

Your moral connotations are backwards. Elastic did a bad thing by changing their product from a FOSS license to a proprietary license. Amazon did a good thing by forking the last FOSS version and maintaining that one. (Yes, it's weird to think of Amazon as the good guy, but even a stopped clock is right twice a day.)