That was my exact thought while reading it. But after a bit you have to believe that at least Elon "believes" it is August 2018.
For all the doubters out there, I'd like to make a couple of points:
1: The 3 month/6 month statement came very early into the AP2 software development... only 2-3 months after rolling the hardware out, if I recall correctly. At that time, if you recall, Tesla had just hired Chris Lattner to develop Autopilot, and things were looking very optimistic. I'd be willing to bet that Lattner set Elon's expectations at 3-6 month timeline. 6 months later, after numerous crap Autopilot releases, Lattner is out. A total 6 month setback where zero headway had been made. I blame the 3-6 month tweet on Lattner, not on Elon (who was probably misled, or at the very least, had very optimistic expectations set to him). Once Karpathy took over, within 60 days he shipped a complete rewrite/reinvention of AP2 software. That's huge progress. From there, numerous substantial incremental improvements have shipped roughly every 2-3 months thereafter. Musk said last week that the Autopilot software is exponentially improving. The foundation has been laid, and now it's going to consistently get better. Kudos to Karpathy, and Lattner was the wrong guy for the job setting the entire project back 6-8 months.
2: Model 3 software development. Nearly the entire year of 2017 required a substantial developer resource group devoting to developing Model 3 software from the ground up. 95% of that development is done, so resources can now be redirected back to the generalized software and Autopilot platforms.
Both of those two factors have been the reason why I believe Autopilot has been set back in the way that it has. Now that both of those issues have been resolved, I fully expect and believe that over the next 6 months we will see substantial improvements. Not sure I'd go as far as saying full and complete FSD, but with the resources devoted to it now versus last year, I can't see any reason why we wouldn't see much more improvement.
We will see...