I extremely doubt any gathering over 2,000 will ever assemble outside the stadium or The Star facilities in my opinion. Nothing has sparked that level of public disgruntlement over a three-decade stretch. That is an extremely long time for resentment to build and not produce outrage of that magnitude.
However, an organized gathering of 500 - 2,000 is easily doable. The crowd size would be large enough to attract the attention of local sports media, which national sports media would run with. And it would cause gameday commentators at the stadium and the network sports desk to follow-up in actual time.
It is a more realistic fan display that a narcissist like Jerry Jones would go into spin overdrive to make the issue disappear. His type of mentality would not take it well at all. And his anguish would only grow as long as he would be unable to corral and conceal the picket signs from cameras. Social media distribution alone would bother him to no end. There is nothing like taking control from a control freak.