I read this NN blog from Karpathy a few times, very helpful. My company is doing software and NN, so I have pretty high confidence that Tesla will achieve high level of FSD by end of 2019.
Software can be easily managed by just a small group of talented engineers, and it's 100 times easier and predictiable than volume car manufacturing. Elon comes from software background, and from the Automonous Day it's clear that he and the Tesla team have successfully progressed to a stage that they only have to keep fine-tuning the software & NN to make the FSD better every day.
I don't see any hell in software & NN, and from my 20+ years in software, I can understand why Elon (or any software background guy) would call volume car manufacturing "hell" -- when in software one guy can write the entire operating system (e.g. Linux), you feel really hellish when you see volume car manufacutring is subject to the stupidity of hundreds of suppliers and thousands of manufacturing workers that's just beyond your control.