Once the ball's arc was affected by the impact with the videoboard, it was altered and made irrelevant. Only angle/arc, force and inertia should be considered when questioning how far the ball could have possibly traveled prior to the impact.
How far the ball could have actually traveled can be calculated, but I'm not certain. What I am certain of is that official measurement of punts begin at the line of scrimmage. The ball only traveled 13 yards beyond the line of scrimmage near or at its apex when it impacted the videoboard.