The big walled gardens will have bulk licenses, the small fry and start ups will die because they can't afford those licenses.
That's probably not a problem since you'd provide him with a comprehensive database containing all copyrighted material ( audio, text, visual, computer code) and an algorithm that detects legal equivalents of these materials in your forum in real time.
Obviously this is all speculation and depends on the wording of the law.
- blogs can have several authors and shared responsibility
- small sites have comment sections
- forums and small contributive community websites are a very important part of the participative internet
- small startups may very well create user content oriented innovative services
And none of the above have the power to lawyer up enough, while GAFAM are experts at it.