I don't have much of a dog in this fight as my kid is still in elementary but I do know that Nolensville has to fight against this much more than it benefitting them. There are multiple kids that are zoned for NHS that go to Ravenwood (where they would have went before NHS was built).
NHS is still a fairly new school. This was only the 2nd graduating class to go through the school so they're still getting settled into the proper classification. They won't be in 4A at the next reclassification, obviously. The town is growing very, very quickly so I'd imagine they'll be 5A in the next round and potentially 6A after that but I've heard the county is discussing another new HS to go kind of between Nolensville, Ravenwood and Page. I'm not sure what the zoning for that school would look like or which schools it would pull from the most if it happens. I believe the capacity for NHS is right around 1700 though.