I'll say two things....
One I don't see any way there would ever be a 2nd Carmel High School....it would be very difficult for them to find room to build it at this point, and I don't see the evidence that Carmel will continue to increase in student enrollment much more. I also have never gotten the impression there is a desire in the community to build a second high school.
Two (and this is from my personal opinion on school "quality of life" ....not from an athletics/finance perspective). I've come to believe the "sweet spot" for high school size is right around 2,000 kids. Or maybe a range of a few hundred over or under that. A large enough school you have enough resources to offer a variety of quality programs to your students and community, but not so large that it becomes impossible to still participate in some of the traditional experiences of "high school life". We used to joke about how many trophies you could win with the last 5 kids cut from Carmel's basketball team, or the 2nd best swimmers in every event for Carmel girls swimming, etc, etc. When a school becomes massive...a lot more kids are locked out of those opportunities. There are only so many spots on the teams....so many characters in the play....so many seats on the student council. My 2 cents....likely worth as much.👍