EA and Valve are partnering up to put games and EA Access titles (EA's subscription service) on Steam.
The first big game will be Star Wars Jedi: Fallen Order, launching on November 15. A glance at the title's Steam page seems to indicate that users opting in on Steam will still need to have Origin installed. However, a Respawn dev has stated on Reddit that when Apex Legends comes to Steam it will launch directly from Steam. So We’ll have to wait and see if you really need Origin to play EA titles on Steam. Other title coming to Steam next year include Battlefield V, FIFA 20 and Sims 4.