The fans will come back. This franchise has been a mess for half a decade and a lot of fans have been genuinely upset at ownership.
But this team sold out every game the first 14 years they were here. I know they were fresh and new and loaded with stars, but that still isn't a fluke. As the Avs continue to rebuild their image the gates will reflect that in time.
Denver is a crowded sports market. The Rockies draw 30,000+ 81 times a year, the Broncos draw 76,000+ 8-10 times a year, the Nuggets draw 16,000+ 41 times a year. The Rapids drew an average of ~15,000 for 17 or so home games, the Mammoth have averaged 15,000 a game for ten consecutive seasons, the Outlaws are the biggest draw in Major League Lacrosse. Then you have CU/CSU football and basketball, DU basketball and hockey, etc.
If the team isn't good fans here have plenty of other options, all year round. And that Sunday game was right after a Broncos home game, during the World Series, during the Rapids season finale. There was a lot going on for the sports scene.