Portal VG247 at gamescom talked with director Anthem Jonathan Warner, who confirmed that the game will be a full-fledged demo-version. In recent years, the demos are less common, so this confirmation from BioWare seems particularly valuable. It was received in response to a question about whether developers are planning to conduct beta testing before the release.
So rejoice: Anthem will get a real, honest demo. Given that the release of the game is scheduled for February 22 next year, the demo should also be expected in early 2019.