If you go to Rockstar's website, they don't even list Relax under their products any more. It doesn't even show up in their search. I'm trying to find some concrete info as to whether or not they've discontinued it.
It's probably worth noting that Drank, the product Koma Unwind essentially copied a few years after it came out, pulled out of the New York market a while back. If it were selling well and making that company money, why would they have pulled out? It's not necessarily because of lack of demand, but that's certainly a possibility.
Some folks continue to act as though KU is a magical elixir that somehow transcends reality. I guess it has never occurred to Coke, Pepsi, Monster, or any other large beverage company to have a relaxation drink or to try and sell it in Walmart or in New York City? If it was judged to be a sound money making idea, they would have been all over it already. But large companies like these don't waste a lot of time trying to make people like something for which, as you note, there is not much apparent demand.