"Chinese sales of domestically-built new energy vehicles in 2017 totaled 777,000 units"
To first approximation none of these were Teslas. EVs are being mass produced.
Mass producing a car might be difficult. But the others manufacturers are already doing that.
They need to figure out how to mass produce electronic drive trains (vastly simpler than what they are building now) and batteries. Batterys are more complex, but most of battery production coming online in the next years is Chinese. Tesla is a fraction of what the Chinese are bringing online.
I don't see any reason why Teslas long term potential should be higher than, say BMWs. Mind you, creating a BMW size company from scratch while driving the electric transition and a pace faster than we otherwise could have hoped for are amazing achievements.