So, let's extend this mentality to the Model 3. Why would Tesla introduce the Model 3, a much cheaper model? Well obviously they're doing it because they have a demand problem, they can't sell enough cars to keep up their growth trajectory, right?
So if you frame it your way, it almost sounds correct. But if you think about it a little more, this is really irrelevant. Companies match demand to supply as best they can, because excess of either is no good. So if you're trying to increase supply by building more cars (especially by 50% per year), you need to get more people to buy those cars somehow - word of mouth, advertising, good reviews, new models, lower price points, or whatever else. This does not mean you have a "demand problem" where you are building cars that you can't sell. The phrase "demand problem" or "falling demand" or anything of the like suggests that Tesla is idling factory time or leaving cars on lots and can't think of any way to get rid of them. I do not see this as being the case.