As I've already said mate, you don't need to track the ball if you have as wide angle a lens as possible and as high a frame rate as possible. Neither do you need to anticipate when you're tracking across one axis at multiple times the speed.
Yes, you keep saying it, and it doesn't alter the fact you cannot be perfectly following the line. There will be an angle as it is behind the movements of the players by definition. In order to account for that angle, it will have to be tracked in three dimensions.
You've studiously avoided commenting on why it is that they don't just have a camera in the goalposts for goal line technology and have those multiple cameras around the stadium tracking the ball. It's because it doesn't work, due to the offset of angles, no matter how wide angle the camera might be.