I think you can pretty much recover 100% or close to it these days. However, it will require missing about a year of action, plus another year of playing to get there. Of course, a lot depends on the severity of the injury, the age at the time of the injury, subsequent injuries and mentally trying to get over it and not worry about it while playing.
I hope in the future there will be a better way of diagnosing stressed/compromised ACLs in the future so a good portion of these injuries can be prevented from happening in the first place. It's certainly one of the injuries you never want to see anyone get.