Did the alternative suddenly become banning all EVs? No, the alternative is to not ban any type of car. Unless everyone attempts an embargo all at once, you will have backup options in that case.
The point isn't to be invincible. If you have a diversity of cars, any one kind of embargo will only harm a portion of your car market. If you mandate only one type of car, then an embargo can completely stop your ability to make new cars.
There will be some EVs in that scenario. Enough to tide things over. But in a world with only one option, anything that blocks that one option will destroy the whole car industry.