Movement: Velocity confirmation packet/input flag

While Minecraft moves more towards server authoritative infrastructure, it would be extremely beneficial to include client confirmation when a velocity update from a server is acknowledged. When developing some games, it becomes very difficult to maintain fair gameplay when players have varying latency and can usually gain unpredictable/unfair advantages in certain situations. 

I might be mistaken but I believe there is no current way to acknowledge (without involving very difficult & otherwise heavy math operations) whether a player's client has acknowledged a velocity change that has been requested by the server. This is a very simple feature that can be added but can make all the difference in game development.