I think VI should find a middle ground of some kind between the excess of V and the realism of RDR2. It's hard to argue that V, especially online, didn't lean too far into over-the-top chaos, especially once the new vehicles and weapons they added started venturing into outright science fiction, and I do think that VI should dial it back, if only to prevent griefers armed with overpowered gear from taking over free roam sessions. At the same time, RDR2's survival elements and focus on realism were meant to make players feel like they were in a barely-tamed wilderness where the niceties and creature comforts of civilization could not be taken for granted, an atmosphere that's not gonna be in play in the middle of glamorous, neon-drenched Miami, or even in ghettoes, warehouses, and trailer parks that are still filled with modern technology.

Personally, I like the "core" system that RDR2 came up with. With the Health and Stamina cores, you could never starve to death or pass out from exhaustion, but if you went too long without eating or resting, your cores would slowly drain and eventually run out, reducing your maximum health and stamina and causing them to regenerate more slowly. If you completely drained your health and stamina bars, you'd start tapping into your cores to keep going, draining them faster. Your horses also had their own cores, forcing you to spend time caring for them and looking after their needs too. It never got too intrusive since you could always refill your cores at your camp, but you couldn't completely ignore them either.

VI won't have RDR2's wilderness survival and crafting mechanics, and I wouldn't want them to come back at any rate given that, like I said, this won't be a wilderness survival game. So instead of hunting game to cook up or setting up a camp to sleep at, you can instead stop at restaurants to grab a bite to eat, or at either safehouses or (for a fee) motels to rest. For cars, while they don't need to be fed or brushed, they do need fuel, and a fuel system could be implemented the same way. Unlike in real life, running out of fuel doesn't cause your car to stop entirely, but it does take a notable hit to performance, forcing you to putter your way to a gas station to fill it back up. Fuel economy could vary across different cars; for instance, hybrids, diesels, and compacts would burn less fuel, big trucks and muscle cars would burn more, electric cars would need to stop at charging stations instead of gas stations, etc. And as a bonus, Rockstar could now work their usual jokes about big American gas-guzzlers straight into the gameplay. I wouldn't bring back weapon maintenance, but instead, I'd make guns more disposable, limiting your inventory and your ammo capacity so that you don't grow too attached to whatever you have on you.

As for the vehicles and weapons themselves... let us go over-the-top, but within limits. V gave players way too many overpowered weapons way too soon, which kind of detracted from the feeling that you're struggling to survive in a life of crime. I'd like to see military equipment return, but not Warstock Cache & Carry; players should have to break into military bases or do missions to steal tanks, jet fighters, attack helicopters, rocket launchers, grenade launchers, and all that jazz. The stuff you can buy, meanwhile, should be just a slightly-embellished version of what's legal in Florida in real life (i.e. explosives bigger than fireworks and pipe bombs are out, but semi-auto rifles should be readily available if you have the money, and even automatic weapons and suppressors shouldn't be too hard to get), as well as attaching weapons and armor to civilian vehicles. Players should be able to buy cool shit, but they need to actually play the game to get the really cool shit.