What is the fine-grained topic of the following text: They are geared to produce millions of cars in dozens of different varieties to cater to individual taste and have far too much overhead to sustain such a dramatic decrease in sales.I think that most will be bankrupt by 2030, while startup automakers like Tesla will thrive on a smaller number of fleet sales to operators like Uber by offering standardized models with fewer options. Only return the topic.
The future bankruptcy of traditional car manufacturers and the success of startup automakers.