Forgot to mention - in addition to the other public hints I already enumerated in answering your question on an earlier post, another reason I believe Autopilot 2.0 will be upon us by the end of this year is that back in December 2015 Elon Musk gave an interview to Fortune, in which he was quoted that he believes Tesla will have an autonomous car in two years. By itself this quote doesn't seem to add up to AP 2.0 hardware showing up in the Model S by the end of 2016 - but if you add this to the other bullet point items I think it is another piece of supporting evidence.
In December 2015, two years away would be December 2017. End of 2017 is when Musk has promised the first Model 3 deliveries. Model 3 Reveal Part II is coming at end of 2016 and will most likely reveal a Level 4 self driving car if you believe Musk's December Fortune quote:
"Musk wouldn’t reveal details about the next generation of autopilot. That, he explains, “would be a major announcement.” But he did tell Fortune where Tesla will end up. "We’re going to end up with complete autonomy, and
I think we will have complete autonomy in approximately two years.” That doesn’t mean city streets will be overflowing with driverless Tesla vehicles by 2018 (coincidentally, the company’s Model 3 should be on roads by then). Musk expects regulators will lag behind the technology. He predicts it will take an additional year for regulators to determine that it’s safe and to go through an approval process. In some jurisdictions, it may take five years or more, he says. Musk adds an important caveat—one that raises the standard of what it means to achieve full autonomy. “
When I say level 4, I mean level 4 autonomy with the probability of an accident is less than that of person,” he says.
So I'm guessing Level 4 hardware baked into Model S/X by end of 2016 to avoid the Osborne effect and also to build a year of fleet training data (perhaps running in the background in simulation mode) before the Model III begins deliveries. If Musk reveals only a slightly more advanced intermediate Autopilot for Model III in the "reveal part II" he will Osborne the Model III itself as soon as someone asks him "Well, you said Level 4 autonomy by the end of 2017" if his reply is "Yeah, well, the first Model III's will only have a slightly more advanced Autopilot - we will ship Level 4 hardware in the Model S at the end of 2017 but Model III will have to wait a while longer."
That response wouldn't be feasible - he would then Osborne the Model III. The only way all these hints fit together and do not Osborne Tesla in one way or another is if Model III ships with Level 4 hardware from the beginning - which would seem to require Model S getting the hardware at the same time as Model III Reveal Part II at the end of this year.
Also, if Model S/X get Level 4 hardware at the end of 2016 it will only build even more excitement for Model III - it's the best of both worlds for Tesla. Gooses existing car sales and builds even more pre-orders for the Model III.
Finally, if the Gigafactory really reduces Tesla's battery costs by 30% and starts building the Model S/X battery packs this summer - well there's your additional margin to allow Tesla to pay for shoving more cameras, computers and sensors into the Model S this coming December.
How this dovetails with a reported simple two-camera upgrade seen running around? I dunno. Maybe we're going to get a simple "1.5" patch fix retrofit to add reliable forward stopped-object detection to existing Autopilot 1.0 cars, but the "full enchilada" Level 4 capable hardware will show up in December.
Elon Musk Says Tesla Vehicles Will Drive Themselves in Two Years