My list, without putting a lot of time into it:
Wolf Run - well-known Indianapolis course. Why did this particular private course not survive? Given the strong market golf is enjoying right now I wonder if they'd hung on another year or two the course would still be open. Or maybe a developer was just dangling too much money in front of someone.
Riverside - Indianapolis muni. At the time it closed there were 3 18-hole munis (Riverside, South Grove, Coffin) and a driving range/par 3 course (Riverside Academy) all in close proximity. Maybe the city's budget demanded something had to go. Like Wolf Run, I wonder if post-Covid the same decision to close would be made.
Indiana University - the one there before the Pfau course. I think once Purdue built their Dye course the IU alumni weren't going to take it lying down. At least this time a course was not simply closed but replaced with something clearly better, if also much more expensive to play.
2 9-hole courses in Carmel, IN - Mohawk Hills and Sunrise. If you're at all familiar with the north side of Indianapolis you won't be surprised that they are both now housing. I liked them as they provided an inexpensive option for a quick 9. Sunrise in particular had some well-done holes, and had a nice driving range to boot.
Coffin, The Fort and Brickyard Crossing all replaced previous courses, but I never saw those.