The FSW system pre-EE involved a NOC list. So your NOC had to be on the list to qualify. Selection wasn't based on points but FIFO (first come first serve), meaning IRCC would open up the application process on a specific day and they would have caps for each NOC. So people would then race to get their complete applications in before their NOC hit the cap and there were no more spaces. IMO they are unlikely to return to that model (i.e. FIFO). If they do go back to a NOC list, then I think they'll still select people based on points but on top of that a person will also have to have work experience in one of the NOCs on the list. Of course I'm just guessing. Who knows what will happen.
In terms of which NOCs were on the list, this changed from year to year based on which occupations were in demand. So just because something was on the list back then doesn't mean it would be on a list now. If they go to a NOC list, that will be based on what occupations are in demand now.
Anyway, I did some searching and here's an article from back then that shows the NOC list that applied in 2015.
https://www.cbc.ca/news/politics/sk...tions-ahead-of-express-entry-launch-1.2673822