I work with people who work for oil companies. I have heard them say "we used to dream about projects we could do if oil ever got to $20/barrel" (meaning got as high as $20/barrel). So, I think this "floor" is very low, and we're going to see extremely low gas prices before its over. As I say, I really do think oil is trying to kill the electric car, but I know I'll get shouted out of the forum for it so I don't repeat it too often.
The movie Who Framed Roger Rabbit revolved around the building of freeways in Southern California. I saw it in the theater after moving to Seattle, but I grew up in LA and knew the history of the LA streetcars. One of the characters made an ironic comment about nobody would shut down Los Angeles' excellent trolley system. I found it very funny, but got a lot of dirty looks in the theater because nobody else got it. (The movie is full of LA inside jokes.)
GM, Firestone, and Standard Oil , Phillips Petroleum and Mack Trucks formed a shell company that bought up the trolley system and shut it down. Then they pushed to build a freeway system in Southern California. I don't know if the oil companies and other interests are actively trying to kill off EVs, or just making the playing field more difficult. They certainly aren't helping in any way. And the foot dragging by the major auto makers could be chalked up to momentum in the way they are currently doing things. Right now EVs are still a tiny fraction of the market. Tesla's market share is only 0.07% of the global market and may reach as high as 0.8% once the Model 3 reaches full production. The entire EV segment is down in the noise of sales figures.
Car companies are making money making ICEs. Just like Kodak was making money selling film when digital cameras were expensive toys.
I've written before about the three phases of a company's life. Most of the car companies in the world are in the bean counter phase. MBAs run most of these companies, not engineers. They are only interested in making as much money as possible doing what they have always done. Innovation costs money and cuts into profits from selling ICEs. They won't change until they have to. If these companies were in the engineer phase, the CEOs would be technical people who see the handwriting on the wall and would be investing heavily in changing.
Only problem I have with your argument is that you don't seem to realize virtually nobody knows this (that EVs are better). We EV drivers are such a minority its hard to over-state how little knowledge of EVs there is out there. EVs can't replace ICE vehicles until what you and I (and the rest on this forum) know is common knowledge, which may not be for decades to come...
EVs are still a fragile phenomenon and may not make it. That's the way I see it anyway.
I know a lot of people who have zero interest in a Nissan Leaf or Chevy Volt, but they lust after a Tesla. Most EVs appeal to the eco-consumer. They are designed to be billboards announcing your greenness to anyone who sees the car. They are designed to be cars for people willing to make sacrifices to save the planet. Some sales go to people who want to save money on fuel and are buying a commuter car. Those people have been buying ICEs since oil prices dropped early this year.
Tesla does appeal to green car buyers, but they also appeal to a much larger audience. There are quite a few performance car fans buying P85Ds and P90Ds. There are also people who value car safety who are interested in the Model S/X as well as people who want good storage capacity, but don't want a big bulky SUV. Tesla also has a lot of appeal among tech fans.
I run into Tesla fans just about everywhere. Just mention Tesla and people go nuts telling you how much they love the car. Even people who hate cars love Teslas. I had to take a taxi on a recent trip and the driver made some negative remark about how the eco-nazis all want us to drive electric cars. I mentioned that Teslas are nice though and he spent the rest of the trip going on and on about how a Tesla Model S was his dream car.
Even if a lot of consumers don't know Nissan Leafs have some pretty good advantages over ICEs, most people do know Teslas are superior to anything out there. I see a massive pent up demand for the Model 3. If it's as well designed as the Model S, Tesla will not be able to keep up with demand, even if the bottom drops out of the oil market (which is somewhat unlikely). Low oil prices might make Model 3 sales a little softer, but not by much.