While that speculation is plausible, another view would be that companies would offer quality content without tracking users and invading their privacy (how many paid services still flood you with ads?), and possibly free alternatives would start to come up.
From your point of view, free open source is something that wouldn't exist
The hobbiest websites will not go away. Open source existed long before the internet.
What you are left with is the hobbiest websites or the mega brands that want to funnel you into their ecosystem. To offer anything that cost resources that you are willing to spend you must be a megabrand using this as a loss leader opportunity.
I don't think we want that world. We may think we do but look at what happened in Mr. Robot.
From your point of view, free open source is something that wouldn't exist