In Canada it's still quite big, although you have few chains doing it now. Cars still rust though, but won't show it for at least 5 years, many won't show rust for 10 years. Notice I said show, as in not easily visible when casually looking at the car. However, once you start looking at the door pinch welds, or underneath the car, you will find rust as soon as 3-4 years.
New cars are definitely better protected from the factory, but also, people tend to trade them in every 4-5 years, so these people will not be interested in rust proofing. The money now is in clear bras, tinting, vinyl wraps. Proper rustproofing is messy so it ruins that new car experience.