Tesla has decupled (ten-fold) its weekly production rate every three years, and there is no fundamental reason why this pace of growth cannot continue. If it does, then we can expect 500,000 annualized rate by the end of 2018, 5 million by the end of 2021, and 50 million by the end of 2024, but let's say 2025 to be conservative. Combined with the fact that full self-driving will allow tomorrow's vehicles to be used up to 20x more than today's cars, which are parked 95% of the time, 50 million annualized production effectively equal one billion annual units by 2025, which is the current population of vehicles in the world today. Note that I did not even mention tomorrow's Boring tunnels, which I expect will comprise majority of "ground" miles traveled by 2025.