In any event, the market for quality chocolate has exploded in the past 5-10 years. Not very long ago, if you wanted decent chocolate, you had to buy it mail order or go to a very few handful of specialty shops. Now I can buy Valhrona bars at my local drug store, right next to the Doritos and the canned pop.
I think Lindt was a real pioneer in this area, since they were the first ones to make fine chocolate mainstream like this.
Far from getting worse, the quality and quantity of good chocolate has just gotten better and better.
So people who want real chocolate will continue to use the good stuff. Even if you're on a budget and can't afford those brands, it's unlikely that even the low-end brands like Bakers are going to risk their market by using vegetable oil. Even the people I know who use Bakers would probably switch if they bastardized their product.
It seems to me, this will only affect the candy-bar market. But so what? The court of public taste will render a verdict. If the product still tastes good, people will buy it. If it doesn't taste good, then people will not buy it and the candy-bar companies will lose money. If I'm eating a Hershey bar (I love the Hershey with almonds!) then I'm not doing it to savour some deep sophisticated chocolate taste anyway; it's for a sweet childish treat.