If they are going to keep it real, then they have to keep snipers that have a rapid response. What they need to add is weapon customization, and more customization other than helmets. And maybe some more Multiplayer modes. KEEP VEHICLES OUT!! GR4 doesn't need to be tainted with something so stupid.
I enjoy co-op in all game, especially military shooters, so I think they should add more co-op modes as well. Not just a horde mode, but objective based co-op that up to 16 players can assist each other in. More players in the game, the harder it gets.
Over-the-shoulder can stay, but have the option to change the camera angle. Larger maps would be nice, but also different environments. Oh, and make the ranks better, were it actually feels good to rank up. And wayyy more guns please. There just aren't enough assault rifles and they all feel the same to me.
As for the single player, General Martin can stay, he does add more to the lacking story. He gives the story emotion and if he wasn't in there doing what he does, I probably wouldn't have cared so much on what the war was about. Since there are no actual cut scenes, they need to keep him. But for GR4 they should have a stronger story. So its more enjoyable.
Thats what I think. I've played Ghost Recon 2 and up, so I think they should go back to those and see what was so great about those.
If you don't like my input, I'm sorry to hear that. lol