I have lived in Denver most of my life. I don't remember anyone ever being seriously concerned that the Broncos would ever move. There would have been riots in the streets.
I think most people realized a new stadium was needed. It passed by a large margin if I remember correctly, and Bowlen put in over 90 million of his own money and the sales tax, (which expired last year) covered 365 million and Invesco paid over 200 million for the naming rights.
All the speculation on moving the team or was all smoke and smoke and mirrors by the lawyers.
I really do not remember anyone thinking that the Broncos were going anywhere.
Also, I remember my Dad saying that the opposition to the stadium tax was politics as usual. Just another topic to rile up anti-tax supporters for the next election cycle.