The dates and details for the Public Demo are available.
This might be a sort of stress test. The free Anthem demo will go live on Friday, February 1 with the servers shutting down on Sunday, February 3. Players will start at level 10 and will have the opportunity to get to level 15. Progress will not carry over to the main game.
Personally, I am still on the fence for this game, but the free demo will help to sort that out.