It's certainly made me buy less UK Dr Pepper in Australia (I find artificial sweeteners generally unpleasant). Many places down under that sell it are now stocking US Dr Pepper instead, which suggests it sells rather better.

I avoid the reduced-sugar ones. Actually these days I tend to buy the little miniature 150ml Coca-Cola cans. Original recipe but only 15g sugar as there's just less of it. Portion size is just as important as concentration!

It completely killed my soft drink buying habits. So it was either a success or failure depending on how you look at it.

I can’t stand the reformulated sweetened drinks. The flavour profile and aftertaste is completely different. I wasn’t a huge consumer of soft drinks to start with, but now I consume absolutely zero.

This is a win from a public health standpoint also.

I don't think this had the desired effect for me (or maybe it did). When I have a coke, or other soft drink it's generally because I want the sugar and caffeine, for instance part way through a long drive or during a night out. Generally I drink water, tea and a little coffee. I don't really want to be eating/drinking any artificial sweeteners. I have a hunch that this is not good for you and adjusts your taste to wanting more sweet things, so I tend to avoid. Regular Coca Cola still tastes ok, but now all promotions tend to be on sweetened drinks. Drinks such as Irn Bru have been ruined, as there is now no full sugar version available.

Unfortunately they didn't take the opportunity to reduce the sweetness. Here in Norway I can buy flavoured water without any sweeteners at all, neither sugar nor artificial. But when I visit the UK all I can find is either plain water or something sickly sweet.

The industry is already a step ahead on this stuff. I'm sure they have reams of market research that say "If a tax appears that causes Coke to be $1.49 per litre and Diet Coke is $1.29, there's a nontrivial amount of customers who will skip the soda rather than switching to the existing diet brand." So they need a product they CAN slide in if the shoe drops.

They brought out "half-sugar" sodas about 20 years ago (Coke C2), but they hit the market with a thud. I suspect that the recent "Zero Sugar" brands are intended to fill the same spot. Notice how the branding is much closer to the sugared brand than the diet brands, and TBF, they're a lot more comparable taste-wise to the sugared versions than Tab or Diet Coke ever were.

There's little case for introducing these products if it's primarily going to cannibalize their existing brands and consume already limited shelf space, unless there's some long-term appeal in it. But if there's a sugar tax, or some dramatic economic fallout that makes sugar ahistorically expensive, watch as the default position on the vending machine suddenly switches to suddenly Coke Zero.