I think it would decrease, but not as much as you'd think.
When most cars are "totaled," the car itself is sold for salvage. If it can be fixed relatively easily, the car will be purchased at a salvage auction, fixed, and resold.
If it can't be easily fixed, the parts that can be salvaged will be resold to other autobody shops.
While the consumer might be "throwing away" the car, the car itself isn't generally being thrown in a landfill until all of the functional parts are reused in some way.
When most cars are "totaled," the car itself is sold for salvage. If it can be fixed relatively easily, the car will be purchased at a salvage auction, fixed, and resold.
If it can't be easily fixed, the parts that can be salvaged will be resold to other autobody shops.
While the consumer might be "throwing away" the car, the car itself isn't generally being thrown in a landfill until all of the functional parts are reused in some way.