I have watched Mesivtos open and fold over the years here in CT. A few local parents decided they didn’t want to send their boys away after 8th grade. So they hit up the local Baal Batim and opened schools. In 6-8 years the schools would fail (usually after the first group of local boys had graduated and the original group of parents lost interest).
My older brothers went to Mesivta in Brooklyn, but did not live in a dorm, they lived with my grandparents who lived within 2 blocks of school.
I went to Mesivta in New Haven. My two sons went to Mesivta in Brooklyn, they dormed during the week and spent Shabbos with my grandparents.
The only boys who I noticed being sent to Mesivta in New Haven during the 70s and 80s were those from troubled backgrounds, but whose parents could write a large check. The Litvish Mesivta (along with day school has closed down amid scandal and the RY is in a state jail cell for what was done to vulnerable students in the dorms.
I would never willingly send a 14 year old off to live in a dorm somewhere and attend Mesivta in these times. I might consider boarding with a family I have vetted, but would prefer they live with relatives. My grandsons of that age are Brooklyn and living in my sister’s home during the zmanim.