No way--the Coliseum has hosted TWO Olympics. It should be a historic site, IMO. But I've also heard that the basic renovations they've done have made a difference.
As far as visiting fans in AZ, it depends on who it is. Raiders, definitely a lot. Chargers, most likely since both their past and present market will be close. Rams, yes because of the LA, STL, and AZ overlaps. Vikings, I'd assume so, since there are many Vikings fans in the Valley during football months. Though I actually wonder how many would then be cheering for the Cardinals against the team that betrayed them...