Who trained the first emulsion chemists? No one, they learned by trial and error (probably lots of error). If there is ever a need for lots more emulsion chemists, they will appear.
On the subject of trial and error, Edwin Land (Polaroid) didn't like to find a solution immrdiately. He liked to have lots of errors so he knew the process inside out. If you come up with an instant solution, you don't the the variables and limits of your process.
I tend to specialise in the error side of things!