If people actually gave up on the deadly sins, wouldn't that spell the death of capitalism?

I agree. If this is a question about Christianity, then where would you put a christian capitalist? A marketer would use deadly sins to mean something else, not because he is Christian, but a capitalist. That's marketing. McDonald would not go bust but would have a different business in a month, and if it would becomes a chain of food distribution to the hungry and needy, that would take the real Christianity deal.