Soon enough, if it hasn't already.

I don't think it has already, but it will soon enough.

in 2 weeks.

Because only MK8 is available digitally

Watch Dogs can't be bought in the interweb, disc only.

right?

Well VGChartz only tracks physical sales of the games so it's possible that it already, or is very close to outselling the PS4 version of Watch_Dogs

That's what I call tunnel vision.

If you you add digital for MK8 then you need to add digital for WD too.

I think the first week of August.

Within the next 6 weeks.

Hardly tunnel vision. It's just pointing out facts that should be taken in to account when talking of numbers here. It could be very close, and is very close at the moment in phsyical sales. Watch_Dogs will slow down significantly faster than Mario Kart 8, as evidence shows already. 

Should be anytime soon; probably 4-6 weeks depending on what NPD says.