It would punish Facebook and send a strong signal to other social networks. But Zuckerberg continues to have his baby and can compete on fair terms with rising social networks.
The US Government retains its mass surveillance tool, probably their main concern.
Voters get to keep using Facebook and feel like something has been done. Their representatives look like they’ve responded and everything goes back to normal.
Users can vote with their feet if they still feel so inclined, and use Instagram and WhatsApp instead.
New startups could compete in the space knowing that they weren’t facing one behemoth.