I think the democratic party is putting out feelers right now for a candidate to support for 2020. They just tried it with Oprah as well.
I would love to see Zuckerberg go up against Trump. He would have no social justice cards to play. He's white, rich, male, and straight. Outside of Bernie's democratic socialism, the only thing the democratic party has left to play is identity politics. Zuck has no points on that scoreboard.