Ideally, this idea would be applied to all vehicles that have auto-ranging capabilities; however it is most important to the AA tanks as they are required to lead and compensate a lot, making it obvious.
However, most (if not all) of the armor have gunner optics that are fixed to the turret. A possible solution would be to have a HUD element that moves ahead of the target, showing where the gunner must aim to hit the target.
I don't know how these things work in real life, and if anybody knows how it works and/or what the gunner sees (for example, the view through a ZSU-23-4 Shilka's optics) please write it below.