I have taken Ice Dance classes or clinics from two different sets of Russian coaches, and two sets of American coaches.
Both Russian-taught classes were very well organized and were very good, but they emphasized skills (including swing rolls, BTW), rather than Dance Patterns. (Part of the issue there is that almost all the students were female.) The classes were popular in part because the coaches had high level competitive credentials (a Russian champion in one case; an Olympian in the other), in part because they had a very disciplined style. Both took the one room schoolhouse approach to dealing with the wide range of skill levels - ranging from basic strokes to advanced drills that most of us couldn't do. In one case, the coach's Olympic hopeful students were encouraged to be available to teach short lessons to the group lesson students, which also helped make the classes very popular.
One of the coaches was once forced by management, at a student's request, to teach the Dutch Waltz pattern - but added twizzles into the side pattern to make it harder, so no one would make him do that again.
(One Russian coach told me that the [Soviet era] Russians didn't use low level dance patterns in their training. They started with drills, and didn't move to patterns until they were ready to compete the International level dance patterns.)
He could have continued the classes, but chose to devote his time to Internationally competitive teams instead.
The other team of (3) coaches (at Wheaton) continues to teach group classes - but mostly to very competitive young couples, whom they also coach privately, though upon occasion they have offered a 4 day adult clinic, with on and off-ice training.
One American coach, a very long time ago, did teach ice dance patterns, in College Park. But ice dance isn't popular enough here to do that. A number of local rinks have recently offered such lessons, then canceled due to insufficient interest.
The other American coach group sometimes teaches ice dance classes, as well as freestyle classes, at a relatively low popularity rink in the summer (Piney Orchard). Most of the coaches aren't especially famous, and I think it is of borderline economic viability.
Another rink around here used to offer fun and fairly popular adult free-style classes, with very interesting choreography. But I think the rink (Benfield) was not popular the rest of the time, and closed.
Another rink, up in Baltimore, had group lessons taught during club ice, and were in large part adult. They were fairly popular, including sessions taught by Robert Oglevie, a well known coach who also wrote figure skating books (and most of the original USFSA Basic Skills manual) that used to be very popular. But that rink closed too.
Another rink around here (Cabin John) has school figures classes taught by a coach I used to know. I assume, but am not sure, that they are largely adult. She didn't have high level competitive credentials, but she was double-gold test, and very good at teaching, and it is a very popular rink.
So clearly, if you get the right coaches teaching unusual and interesting classes, in a large metropolitan area where skating is fairly popular, you can attract a sufficient number of adults to run popular adult classes - ice dance or freestyle. (BTW, there are also popular speed skating classes around here. I'm not sure how popular the adult hockey classes are, but there are a bunch of adult hockey teams. I've not heard of any Pairs group lessons.) But you need coaches who are very, very good at teaching group lessons to people with a wide variety of skill levels, who are willing to spend a lot of effort organizing the class, and it helps a lot if the coaches are famous too. But such coaches are superstars in their own right, and have to be convinced that it is worth their time and effort to do it right, because they have other ways of making a good living as a coach.