i think they could pull sights off in gta. like in max payne 3 if you had a red dot sight whenever you aimed it went into first person view.
If there is weapon customization, I say, by default, the weapons zoom traditionally, then you can buy scopes for assault rifles and any non-sniper rifles (and perhaps, upgraded scopes for sniper rifles). Would be nice to have separate weapon slots for assault rifles and regular rifles, as in San Andreas, assuming they bring back the rifles. I could see Trevor picking off enemies with a hunting rifle because there wasn't a sniper rifle available.
Fallout: New Vegas' level of customization would be nice. Nothing over-the-top.
I like the idea of being able to have an AR and a sniper rifle, really annoying having an SMG and a sniper rifle and lacking the range with a full auto weapon. Have you played Max Payne 3? The weapon customisation in multiplayer is nice and simple and that's a 3rd person game so I can see them using the same sort of system.