I think you underestimate how far Tesla already is:
- Northvolt doesn't have a factory for production yet. When they plan to open in 2020, Tesla is probably already constructing its second or third battery factory. Also mind the amount of batteries needed for mass-market EV.
- Tesla is said to have a significant edge in battery production cost, compared to its competitors. Given that the batteries are the most expensive part of an electric car, that's significant.
- Without checking all european car manufacturers: At least the first mass-market EV from VW is expected to hit market in 2020.
- Northvolt doesn't have a factory for production yet. When they plan to open in 2020, Tesla is probably already constructing its second or third battery factory. Also mind the amount of batteries needed for mass-market EV.
- Tesla is said to have a significant edge in battery production cost, compared to its competitors. Given that the batteries are the most expensive part of an electric car, that's significant.
- Without checking all european car manufacturers: At least the first mass-market EV from VW is expected to hit market in 2020.