Potassium Cyanide, however, is readily replaced by (slower working but much safer) sodium thiosulfate. The various additives to the salts that go in collodion seem like limiters -- I've seen formulae that include cadmium, for instance. Nitrates in general may become hard to source (along with nitric acid to make them), but you can always start from potassium nitrate which you can make yourself.
I don't think "decline" is the right word -- worker health restrictions are causing more trouble that loss of industrial capability in general. Both Fuji and Adox have had recent product changes because necessary chemicals became either unobtainable, illegal to distribute, or illegal to import into a major market (even in a finished product). Seems to me I've read of Kodak having similar issues.