Even NBA arenas are trending smaller.
FiServ in Milwaukee capacity is 17,385 where as the one it replaced, Bradley Center had 18,717. The Clippers are going to move into the Intuit Dome, 18,000 capacity, down from 19,000+ at Staples.
I could envision a joint Timberwolves-Gophers project, something along the lines of the Moody Center in Austin, TX which seats 10,763 for the Longhorns, but can be expanded to 16,000 for NBA games, such as when the Spurs have played there.
State Fairgrounds would be a potential site.
It's a longshot. Just throwing it out there as a possibility.