Hunting was built as a load-bearing system in RDR2. It hasn't been anywhere near a load-bearing system in GTA games. Whether GTA 6 flips the script on that is pure speculation - we hedge our bets.
Arguments for
The wildlife you can see in the trailers is detailed. Florida has an actual hunting culture. Rural regions need activities that tie into gameplay loops. Hunting can help.
The RDR2 pipeline is already integrated into Rockstar's tools - repurposing parts of it for GTA 6 would be more cost-efficient than building from scratch.
Arguments against
GTA's players aren't inherently a hunting audience. Hunting requires design energy that could be spent elsewhere on city content. Backlash over animal welfare is a legitimate PR threat to Rockstar.
Games in the GTA series haven't historically featured hunting. That's a powerful precedent.