Since then, USFSA has climbed down from its Olympic tower and copied most of ISI's program.
USFSA LTS has been around for many decades.
ISI still has some advantages from the skater's perspective - it has clear, more or less easy to read instructional materials, and a DVD everyone in ISI can buy. And they cost less to join, less to take lessons through, less for clubs to associate with them. And they have a number of "fun" categories.
But what is an advantage to skaters is not always an advantage to coaches.
But I'm not sure of all the reasons USFSA has been taking over group lessons so many places. Perhaps advertising? - when you watch a USFSA or ISU event, they advertise USFSA, but not ISI.
If so, ISI is quietly letting itself die.
Or perhaps it has to do with the coaches. Most of them were very good competitive skaters who competed within USFSA - as you must within the USA at the highest levels.
If a coach has hopes of creating elite level competitive skaters, they have to pay for a coach-type membership in USFSA, and be trained and certified for that by USFSA - and they would have to do similar things for the ISI if they wanted to teach ISI lessons too. So it makes sense for the coaches and figure skating directors to do what is most convenient for them, which is to just go with one organization.