EA and Valve are partnering to put both games and EA Access (EA subscription service) on Steam.
The first big each for this initiative is Star Wars Jedi: Fallen Order on Steam, which will launch on November 15. A look at the title Steam page seems to indicate that users who opt for Steam still need to have Origin installed, similar to how games like Division 2 direct you through Uplay to play.
Other great titles such as Apex Legends and Battlefield V will arrive on Steam next year. Do you still want to play in Origin? No problem, you can play with Steam users.
You can read more in the official publication here.