It’s funny. You make it sound like there’s some kind of law saying all cars must be junked at 200K. In the United States, that isn’t true. It’s still a free enough country that you can keep your junker and pollute the air as long as you can pass inspection, however often your state requires it. And if you don’t put it on the road, I guess there are no restrictions on pollution.
But newer cars are more efficient and less polluting. They may or may not cost less to operate. Probably cost more because of the cost of buying them.
But there is no law in the US saying you have to junk your car at 200K. So, you’re good unless you live in another country where there is such a law. I’ve never heard of such a thing, though.