Based on recent developments, two predictions I made very likely will turn out to be incorrect.
I predicted Tesla would deliver the first Model Y by March 31, 2019. This prediction was based on what I understood to be Tesla's plan to develop an SUV version of the Model 3. Elon recently explained that Tesla will be re-designing the Model Y from the ground up and will be using a full-blown version of alien dreadnaught production. It also announced that the reveal for Tesla Semi will be this year, which will precede the Model Y. With all of these complications, Elon predicted Model Y deliveries will begin in 2020, maybe late 2019. But Elon continues to predict that Model Y production will begin in time for Tesla to deliver 1M vehicles in 2020 so in the big picture Tesla remains on track.
In March, I predicted that Model X sales would exceed Model S sales by Q3 based on my belief that demand for X exceeds S at the same price points, and my understanding that the price gap between entry level S and X would shrink after the S60/60D was discontinued:
In Q3 2017 Model X deliveries will exceed Model S deliveries (and may happen sooner).
I believe demand for X already exceeds demand for Model S at comparable price points, but this has been masked by significantly lower price of the entry level Model S (~$68K v. $88K US) and Model X production constraints.
The price gap between entry level S and X should narrow significantly after the S60/60D is discontinued and improved production efficiency of Model X will allow Tesla to steadily increase Model X volume.
But instead of shrinking the price difference between S and X when it discontinued the S60/60D, Tesla significantly decreased the price of the Model S 75/75D, without a comparable decrease to the X75D. This not only gave the S a much lower entry price point than the X, but also significantly changed how S and X stack up against each other with the same battery size.
I continue to believe demand for the X substantially exceeds demand for the S at the same price point, but the $13K difference between an entry S and X ($69.5K v. $82.5K in the US) is so large that it is unlikely that the X sales will exceed S sales soon unless the price gap drops, unless it gets "lucky" in Q2 as Tesla works through the backlog in X orders.
Incidentally, the high entry level price of the X will also mask its success against other premium SUVs, most of which have significantly lower entry level price points.
I will make a note in the spreadsheet, but I am not going "update" these predictions to something that will prove correct and remove them from the spreadsheet. I continue to believe that undermines the value of this thread.
One lesson from these two likely incorrect predictions is that Tesla's plans are constantly evolving, which makes certain types of long-term predictions especially challenging. But that's half the fun