I am very torn. I know the Pit would still be there for graduations and whatnot, but like the OP said, it doesn't sit with me well downgrading capacity by 30% for a school with 40k students. And I know we don't fill the current building, I know it looks even worse for women's games, I know live attendance is going down across most sports at both the collegiate and professional levels.
I've never been a collegiate athlete, but if I could imagine putting myself in their shoes, I would think if the locker rooms and training facilities are above par, and there's a good fanbase, then the arena shouldn't matter as much. Especially considering all of the historic (in terms of memories and age) gyms that host your Dukes, and so forth.
I'm not opposed to a new arena if the money's there -- although I do find it kind of funny making a fuss about having private suites to watch unpaid athletes -- but do fear it creating just another excuse for an on-campus student not to go to the game if they have to go across the highway. Of course for football, there's 10 fewer home games creating more urgency, every game's on the same day of the week, and there's tailgating. I know I say all this like they are turning dirt tomorrow morning, but I'd like to see some fuller houses at the Pit as the program continues its success before putting too much energy into a new building.