Yeah, my total costs are probably not going to go down much if at all (though my expected parental contribution to D22’s college tuition is actually less than her private school tuition was). But I am hoping that it will all feel more predictable at least in part because in addition to our grocery bill, our takeout bill has skyrocketed this summer. If nothing else, maybe it will be one fewer pizza to order on pizza night. 
More seriously. She will be responsible for all indirect and unbilled expenses at college (like books/supplies, eating anywhere besides her meal plan, any social life or entertainment, laundry, whatever). I do not plan to give her any spending money at all.
I’ve already set up a monthly payment plan with the college to cover my part of her billed expenses. So I know what that monthly tuition payment is, and that number is factored into the family budget. And I am hoping (perhaps naively) that with the exception of that monthly payment, I won’t have additional expenses for her and my daily household budget might drop a bit for food and utilities and the various random often unexpected stuff that has cropped up during her middle and high school years.