No tickets, no citations, no money for the city. It'd be the Ferguson administration that would be hurt more than the protesters.
That is exactly what happened here in NJ when the State Police were excoriated for “racial profiling”, which was a great law enforcement process that was oversimplified to make it unacceptable (the primary determinant was out-of-state plates with no visible luggage - a tip-off of drug & gun running - not race itself). When they were called to task for it, they “stood down” - and simply wrote accident reports. City governments in northern NJ IMMEDIATELY saw a spike in gun/drug crime (Newark set a homicide record, and buses had advertisements on the side screaming “STOP THE KILLING”), and the People That Matter simply shrugged; be careful what you wish for.