IHMSA is far from dead.
You'd never know it was still alive around this part of the west (NV). For many years it was a very big thing here at our biggest private gun club, with the state IHMSA director and his wife running the matches. Even used to meet for breakfast and than carpool down to another chapter in AZ for fun matches. At our club it was always standing room only both weekends a month the BB and SB matches were held, with dozens of shooters and near as many spectators at every match. Some of our top shooters competed in the southern CA finals every year. Then a few years ago it suddenly changed, and not long after we totally rebuilt the range with concrete walkways, improved the covered and divided shooting cubicals, installed automatic reset silhouettes, PA system and lighting, etc. Now at a typical big bore match shooters are as scarce as hens teeth, and small bore is not much better.
What changed? For one the director stepped down from running the matches. Even though the gent that took it over was one of the most active competitors and well enough liked by eveybody, people started to fall away. While some left the area, most changed disaplines to BR or SASS, or stopped shooting altogether. I'm one of the later. Without the draw of the IMSHA I saw no need to pay the $150 a year dues. (I can do all my other shooting with less than half the drive it is to the gun club on the surrounding desert.)