It's like a dog chasing a car
I would be fascinated to know just how they plan on collecting on their claim. I doubt that anyone outside of Iran uses a ".ir" address, and I also doubt that anyone in Iran cares what some judge in the US thinks about their register. The Iranian networks will simply set up their national network DNS ignore any DNS updates from outside Iran that would change their own registry, and go on using it as before. As to how ".ir" resolves in the rest of the world would be pretty much irrelevant to most people except to people who want to read Iranian news releases. In that sense it would affect foreign journalists and Iranian expats, but no-one else.
As to who would buy an ".ir" domain from someone other than Iran's official registrar is another good question. People in Iran couldn't see it since their own national DNS wouldn't recognize it. There's loads of low value national TLD name space now. The only real market that I could think of would be for dodgy domains (spammers, pirates, etc.) that no other registrar would touch.
There's also no guaranty that any country outside of the US would recognize the change of "ownership" either. Probably some would, and some wouldn't. The non-changing ones would be doing so out of self interest rather than sympathy for Iran, as they wouldn't want the same thing to happen to them in another case. Some of Argentina's creditors tried to seize one of their naval vessels not long ago. They would definitely have a go at the ".ar" name if they thought they could grab it.
Some multinational companies may individually ignore it as well, if they do business in Iran or have Iranian customers.
The end result could be just exactly what the US has been desperately trying to avoid in their manoeuvrings to retain control of ICANN. A group of countries outside their control would set up a working relationship to decide how the Internet works outside of the US. Once they did that, they could decide to auction off their own ".com" and "dot whatever" names as they pleased on this second internet. There would be gateways between the two (or three, or more) Internets, which companies could bridge provided they pleased the powers that be on both sides of it. It would be rather like back in the days with the proprietary networks such as Compuserve with their walled gardens.
The "Internet" as we know it today exists only because it's convenient for everyone concerned. If a US court went in like a bull in a china shop and broke that consensus, I doubt it would come back together in the form we have now.