The bar is set at 3,500
I asked a neighbor who's very involved with Brown alumni organizing how many he expected to show up for the game. He thought a few hundred. They decided to make a push for the Columbia football game on Saturday instead.
Between the 120k+ STJ area alumni and the Brown/NY metro contingent, I'd have to hope for at least 4k. At the end of the day, college basketball is a big business and, by year five, Norm & Monasch need to fill those seats/benches-or Harrington needs to find two guys who can.