I really hope not as that is the one thing that kills arma 3 for me. I'm sick of being killed by people popping round corners just as the right moment because they can see you from safety.
I was tempted to post a comment over on the ARMA3 forums Ground Branch thread about Ground Branch simulating combat environments more accurately and realistically than ARMA3 does.
Actually, it's a server setting. Don't blame the game, blame yourself for not playing on servers that disable third person view. It's entirely optional. Options are good.