Yeah smartphone, tablet, or MP3 player + speaker is enough, but someone still buy car stereo in future maybe because they think buy a car stereo means upgrading their cars
I agree, people will still buy a car stereo in the future to upgrade a car. But, a car stereo is not be a
must-have upgrade like an automatic transmission or air conditioning for people who live in hot countries like Australia, so some people will be fine with a smartphone, tablet, or MP3 player, and speaker for playing music in a car.
If a driver does not listens to AM/FM Radio, CD music discs in a car, a smartphone, tablet, or MP3 player, and Speaker could be good enough.
I think small cheap cars would be OK with a smartphone, tablet, or MP3 player, and seperate speaker if the built-in speakers are not loud enough and the car is noisy. Cars like electric, hybrid, and newer gas cars are becoming quieter where a less powerful speaker can be good enough.
Many people who buy cheap cars usually like saving money by buying a car without air conditioning, stereo, power windows, power door locks, etc. There are also poorer people who can't afford to buy car upgrades like a stereo, nicer metal wheels, and nicer seats for their cars, but need an affordable cheap car which is safe and reliable.