I'm thinking that the gameplay mechanics are going to be different in FNAF 4.
You have doors back, but the cameras are gone, and in order to close the doors, you have to go up to them and pray an animatronic isn't there and then close the door. Later down the road, you will need to somehow close the closet due to Foxy. You can also peek out of the hallways and use your light to see how close the animatronics are to you.
Making it a free roam would feel strange because in the trailer, Bonnie and chica were down the hall and then moved away from the hall. So I feel as if going down there would be a death trap and you would have to close the doors.
As for the multiple freddys and plushtrap. Well, that's a story Scott can solve by himself.