SN is quite important. It's not like N, it can't be replaced. Even if it gets harder to get, then it will never be impossible. SN is a fundemental part of the food industry, and unless we find something better than it then we'll never run out of it. "Dealers", if you could even call them that, come and go, just like DMC will dissappear at some point.
Also, if I remember correctly, then DMC was ukrainian, I think? I might wrong though, I don't spent much time on this site anymore. But if he is indeed from Ukraine, then it's possible he won't run out of it any time soon, or even ever. Its laughably easy to get such chemicals in western europe countries, especially in ones that aren't in the EU.