Interesting that you mentioned Marquette whose fans continue to use Warriors even 20+ years after the name was officially retired. The link below details a brief history of their name change and it is very similar to what UND has experienced.
http://wiki.muscoop.com/doku.php/nickname/start
"Even current students, who were youngsters when the original decision to change the nickname was announced, continue to chant “Let's Go Warriors” during men's basketball games."