Need to keep in mind that Fox is supposedly sponsoring a separate 16 team post season tourney from the NCAA's version of the NIT.
Also, they need to get rid of games at campus venues for the NIT and Fox's new version as well. Move all of the games to Vegas with their multiple venues (Thomas & Mack, Cox Pavilion, Orleans Arena, T-Mobile) and include at least one team from every conference if the mid and low major regular season champ doesn't make the NCAAs. Back in the day before NCAA tourney expansion in 1975, there were 16 teams playing all the games at MSG in NYC so you could have teams playing 4 days in a row and it was highly popular.
The attendance at that deal would be in the low 100s. You could host it in a high school gym.