Most countries still do, except the US, where we have corn subsidies and sugar tariffs to artificially lower the price of corn and artificially raise the price of sugar (to protect a few growers in the south US).
The other year when sugar prices were near equal to corn, Pepsi and Dr. Pepper distributed soda with sugar only throughout much of the United States. I haven't followed the prices of sugar since, but I would gather the price went back up either naturally or through congressional means.
The commodity price of sugar is ~1.5 cents per can of soda, so I think they could get away with it whenever they wanted (meaning that they would have canceled the products because they weren't making enough volume on them).
Now I looked it up, Pepsi markets "throwback" brands which use sugar.
The other year when sugar prices were near equal to corn, Pepsi and Dr. Pepper distributed soda with sugar only throughout much of the United States. I haven't followed the prices of sugar since, but I would gather the price went back up either naturally or through congressional means.