Tesla is currently valued higher than Subaru, Fiat Chrysler and Mazda; all successful car companies selling much more cars. With the exception of Volvo and Toyota, whose value includes much more than just the car companies (like heavy industry manufacturing, commercial vehicles, Toyote even owns 0.27% of Tesla), only a ~2x increase in valuation is realistic. If they become one of the biggest car companies in the world.

They're not just a car company, they're a battery company who happens to make cars.

If 400% over 50 years = 8%/year is the most optimistic scenario then it's not very exciting.

and with compounding interest, it's only 5%/year.