Maybe I misspoke. motorcycle drivers are auditioned to drive motorcycles, but that doesn't necessarily mean that they will be traditional "biker gang" members. They used some last year in Purge as escorts for the victim truck, two years ago they road around in Survive or Die, etc, etc.
No actual confirmation statements that I know of. Since this is still speculation season, it's very rare for more than one or two zones to be actual IPs.
I'm just saying to believe that there's a better chance bikers may be used in an unknown theme, rather than trying to jam them into an IP that may or may not be coming.