It feels like we’re saying the same thing at different levels of skepticism. Their primary motivation is going to be money as they’re private companies. Most people will stop contributing to an open source project when it stops being important to them. Either its not profitable for them, or its no longer cutting edge, or they just don’t like the direction of the project.
My main point is that private companies can and do contribute to the FOSS ecosystem and can do so in helpful, non-nefarious ways. Most aren’t google, most just want a useful and reliable message queue or database or kernel without trying to profit directly from the component itself and instead just using the component to do the thing that actually makes them profitable.