Cyprinus

The top part - kinda an eye - makes me think of Barad-Dur...

Dunno how it was on release, but later on the Blacksmith was widely available here. If this is the connection you're talking about, adding a tower there would be kinda awkward...

It would just about be the only way to get them, Cirith Ungol itself being nowhere near iconic or memorable enough (for general audiences) to warrant a set...

Didn't the old Leak mention armories and dungeons for the interior, with the minifigure lineup including Frodo, Sam, Sauron and Orcs? Anyway, I'd fully expect a Palantir room and a throne room thrown into the mix, however I could see someone deciding that would be too close to the way Orthanc was set up (even if it would make sense). And while it is true the rescue was at Cirith Ungol, we could easily see them pulling the same stunt they did with the Avengers Tower, where they included Loki's prison cell, though that was nowhere near the building. I'd love it if we get a bunch of Nazgul minifigs in the set, but I also doubt they'd want to include the full Nine - unlike the Fellowship those aren't varied enough for it. I'd also love a set of characters from the Last Alliance (Isildur, Elendil, Anarion and Gil-Galad, maybe throw in Elrond), but I guess a bunch of random, nameless Orcs would be easier and cheaper to make... And something I'd find hilarious and great would be them reusing the Lighthouse setup, so the Eye can truly search for the Ring. But I doubt that would be a thing.