Hair and beard growth system is NOT going to be in GTA 6. It was confirmed in a transcript that Rockstar Games sent Davy Jones of their conversation. A quote from Rob Nelson to TGG seems to confirm this as well. Quotes below:
From Davy Jones transcript, sent from Rockstar: Davy Jones: "Does the character's hair grow naturally?" Rob Nelson: "No. We thought about it, but that goes back to realism versus customizability, and we just thought that, with the pace of this world, it's better to just let you come in and do whatever you want to do." From TGG’s transcript: Regarding hair growth. Rob Nelson: "So, for your hair you can do a bit of stuff in your safe house, cut it shorter, shave it, but if you go the barber or hair salon you can access lots of different styles, it's not that your hair ha