The Open Source Business Model is Under Siege is about the challenges faced by companies building businesses around open source software infrastructure, particularly from cloud vendors like Amazon Web Services, Google Cloud, and Microsoft Azure. The author argues that open source isn't a business model but rather a way of developing and delivering software, and that it's a superior method except for making money. The question is where the subsidy will come from, and common methods include consulting & professional services, support & training, production tooling & monitoring, open core, and Software as a Service (SaaS). However, each of these has its problems. The author shares their own experience with InfluxDB and other projects, including struggling with supporting and producing tooling, and eventually adopting the open core model to make money while continuing to invest in open source software. They believe that SaaS is where the future of open source lies, but successful models resemble open core, using closed source software for managed platforms as a moat against competitors. The cloud vendors aim to make infrastructure software easy, targeting verticals and using open source as building blocks, forcing companies to find new methods for making money.