I have some (what I hope to be) final thoughts on the nylon-12 shortage, but they really are about disrupted supply chains in general rather than nylon-12 in particular. However, since nylon-12 is the subject at hand, I will be specific to that and state that the nylon 12-resin shortage will have long-term damage on all the nylon-12 suppliers. And by long-term, I mean years beyond the time that the Evonik plant is rebuilt and fully operational.
A disruption of the supply chain like this will create a good deal of self-examination for the customers. The biggest outcome will be a "never again" response - never again will they be caught needing nylon-12, unable to get it and having no alternative but to let it impact their own production (or at least potentially impact it).
While many nylon-12 customers thought they would be safe from such disruptions because several different companies sell nylon-12, they never realized that these suppliers were all so dependent on a common feedstock - cyclododecatriene - (CDT) used to make nylon-12, and that the CDT supply was so dependent on one supplier. Since the disruption in the CDT supply, that vulnerability has been made clear and few people will volunteer to get back on the horse that just threw them. All the companies feeling the pinch of the shortage will have either found an alternative material or at the very least examined other alternatives and will continue to examine those alternatives. Those that switched away from nylon-12 will not switch back just because the material will be re-available, as any switch involves a large body of work, paperwork, approvals, meetings... There may be an economic justification for switching back, but any such reversals will be done with much analysis of the risks and how to handle future disruptions and are not guaranteed in any way. Because of these switches away from nylon 12, the CDT/nylon-12 market will quickly change from being in undersupply to oversupply once manufacturing is re-established. (Ironically, that would be the best time to start using nylon-12, as there will be excess capacity.) This oversupply will eventually be sold, but it will not happen quickly as nylon-12 is a non-commodity product, not widely used. Most of the niches in which it can be used have already been found and only time and a big sales effort will establish more.
These comments are based on some personal experiences that I had while working at Hercules. (Hercules again?! It was a pretty crazy year there in Terre Haute for me, wasn't it?) This had nothing to do with the potato chip bags, but involved a customer who is best known for making caffeinated, carbonated, caramel-colored beverages. We were supposedly within 6 hours of shutting them down because of nagging production problems that gradually reduced how much material we made. The customer bought film from us and no one else (this was a time when all the business consultants were pushing "single source supply" as a way to work closely with your suppliers and to build trust). It was to the point that we would make a roll of film, immediately slit it down and ship it to the converter, who then immediately printed it and shipped it to the final customer. Even though we resolved the production problems, the customers clearly saw the risks of relying solely on us, started exploring alternatives and took advantage of those options.
So while the nylon-12 production crisis will be soon resolved, the marketplace will not soon forget the disruption that occurred.