Long way off I say in terms of current CDAF. I've seen figures of say 2/10 second for CDAF that is 200ms! 20fps needs 50ms per frame. I suspect only phase detect can give that for continous AF over the next few years. We also don't know if the ratio of light passing through the mirror can be improved. Currently I believe it is 70% to the sensor. Sony might try and bump that up to 75% or even 80% on the later designs.