I agree that for transportation, there is a long way to go before fossil fuels are displaced as the dominant source of energy. But the cars are already affordable, it's just production scale that's lacking. The Tesla Model 3 is beginning production (this week I believe), and Chevy has the Bolt, which is similarly priced in the $35,000 range and has a slightly better range. As for batteries, Tesla has the Giga Factory which is currently only operating at a fraction of capacity. When it is at 100% capacity, that single factory will be producing more lithium ion batteries than the rest of the world combined. They built that factory because they forecast that demand. The question is how quickly the demand will materialize.
$35,000 for the Model 3 is still a bit high for me. But I have heard that there are additional expenses as well. For the Model S, the battery needs to be replaced every seven or eight years, and this is going to cost you a fortune. Eight years is not a very short duration. But when your Tesla Model S 70 costs around $80,000, you may be expecting it to last at least ten years.
I've had a hybrid car since 2006. The battery system is indeed expensive to replace. Eight years was about how long my car went before the battery system (it is comprised of 100 lithium ion battery cells) was no longer holding a charge for very long and was relying almost solely on the gasoline engine for acceleration. The manufacturer (Honda) replaced the battery cells without charge though since they had determined that the software that controlled the battery system was not configured properly and caused the batteries to be maintained in a sub-optimal way, which cut the battery life short. Because the batteries were under recall due to this, they replaced them all at no charge. So while I got lucky there, it does also suggest that the batteries (in this hybrid at least) are intended to last longer than 8 years. Perhaps with a pure electric cars, they are not projected to last as long because there is so much more charging and discharging of the battery.