Everyone will get a prompt that asks them whether they want to consent to personalized advertising or pay $20/month to use the service. Everyone picks the first because nobody outside of HN bubbles and bored EU regulators cares about personalized ads (or actually prefers them).
Then the EU will start claiming that everyone should be able to use Facebook without advertising and without paying for it i.e. for free or for vastly reduced revenue potential. Eventually Zuck will get tired of the EU because visitors from there won't be worth much, and start to degrade or remove service for them entirely. New products and features won't launch there at all, see Threads for a preview of non-coming attractions. HN Euro-posters will assure each other that this is in fact a great victory.
WhatsApp before it was acquired also demanded an optional donation of 1 USD/year from each person.
That is what people will be willing to pay, and what social media should subsist on.
[1] Annual Report 2022 https://www.patreon.com/file?h=90246790&i=16020862
/s if not clear.