The guy at GAF found out some trademarks revolving around the Mafia series indicating a third one might be on the horizon.
As said above Someone at GAF noticed that there were 4 domain name that were registered named:
mafia3thegame.com, mafiaiiithegame.com, mafiathree.com and mafiathreethegame.com.
While it’s not uncommon for companies to register trademarks and site domains a registration for a smaller game like mafia might actually be a hint of things to come. I’ve never played a Mafia game but if a third one gets announced I might check it out. This is the only screen cap to go of but let’s hope it’s for real.