I think they have been close for a few years already. We are edging closer every year but it is still somewhat Digital. Which is sort of the end of the S curve taking a very long time to perfection. May be in 5 years time I can barely tell the difference.

Edit: May be it is the Real Time Rendering.

But the real innovation is achieving this in hours and not weeks or months.

Sometimes I wonder if we are also getting better at distinguishing artificial humans as time goes on. I remember as a kid thinking that G-man in halflife-2 was almost photorealistic.