Even still, Tesla's plan isn't to become a luxury car company- they've been clear from the beginning that they've started with luxury as a way to bootstrap development. I'm guessing that the 500k cars a year that they're looking for is also going to include those new "standard" models.
I doubt that they plan on 500,000 luxury sales. If so that would pretty much mean abandoning any pretense of having a mass market electric car.
I would hope that they think they will put this towards a sub 40k car, or better yet below 30k which is where many of the smaller electrics are now.
Still a large factor like opens the possibility of packs not certified for cars being given other uses. Put in Texas and reap the power of the wind to power the factory too!
For global auto sales from US manufacturers, I'm guessing that companies like Paccar and Oshkosh are keeping Tesla out of the top five currently. They make trucks and commercial vehicles so people tend to overlook them when it comes to comparing auto manufacturers.
Still, I do agree with the underlying message of your post. It's not like there are a ton of US auto companies left.