You make a good point since we are talking business model. Most do think of the future. This shady business does not seem to care. But heroin was a standard up until about 10 years ago I believe. So it won't go away completely but there may have to be different channels than a street dealer to distribute. Right now the whole street scene (just from what I read as I have no experience with the street after 1990) seems to be at a peak with this fentanyl/xylazine stuff in the US. It is starting to happen in other parts of the world. As poppy fields become less the synthetics will take over. The people that want real heroin again may need to create a channel for that. Right now a lot say the Dark Web is that (again no experience). So yeah, what happens to the small amount of people that did not ruin their tolerance with fentanyl and want heroin? Makes me wonder if the desire is big enough to create a new channel.
One great thing about opiates is poppies do really grow all over. I saw some surrounding the fire station in town. The red ones. Little pods already popping. I also saw a large field off the highway once. If someone gets good at gardening they can at least have a little supply of morphine. I think poppies may be the way of the future. We just need to legalize all natural things like we did with cannabis.