Elons goal is to electrify transport. Which is nice, but to get decent range you need to go large on the battery pack. Or stop regularly and longly for recharges.
Big batteries are expensive.
BMW took a different approach with the i3 and stuck in 22kWh and a 650 cc bike engine they had lying around their parts department. Not particularly economical, but it gives you peace of mind that no matter what charging station issues you get, plan b on journeys longer than 75 miles is that you can stop at a gas station and top up for another 50-75 miles range.
I think theres a possiblilty the EV experience could catch more people if say BMW and other competitors to Telsa started bringing out small 20-30kWh pack cars with 50hp generators, with only final electric drive to reduce all the mess of bits that GM had in the Volt.
It looks quite feasible BMW could bring out an i4/5 for about £40,000. (i3 is £33,000) plus options. stick in a slightly bigger motor, bit more battery, make it more sedan shaped than city, and you have a car the public won't feel anxious about buying. IF it also has say a 20litre fuel tank instad of the i3 9 litres.
As much as I like Telsas approach to go for the full EV, it puts it up the price, well above an smaller Pack plus ICE well until the 2030s.
Then again, I'm pretty sure Telsa recognise this, and that frunk space has been left empty for a reason. Just in case ;)
Could be interesting times up ahead.
[Edit] An EREV is an extended range electric vehicle. Final drive electric with an auxillary power source (usually ICE). Also known as series hybrid.