Maybe next year... I think the initial implementation will simply adding concussions to the general injury list without the option to put the player back in the game similar to "Broken Collarbone," "Torn MCL," or "Dislocated Ankle." With another year, it's likely the injury may be tied to the way players make contact.
Also, regarding wrap tackles: There is still risk of concussion injury. Especially in situations where the tackler hits a player square in the chest and wraps his arms so the ball carrier cannot break his fall. The back of the head is subject to hit the ground with the whip action that causes many concussions on tackles that don't seem to be hard hits.
Overall - I'm glad its in. Madden is an instructive game that exposes many young people to football. Teach them right, right now.
Later