Interesting suggestion. I remember original XCom games having a limit on commanders and captains and other higher-ranking officers, like you could only have one colonel (can't remember exactly what it was) per base.
The character did not differ from the others, but it had an effect of keeping the morale from caving in if a low-ranking rookie soldier died. However, the coin also had a flip-side, which meant that if he died, everything went pear-shaped in an instant as everyone soiled their pants in sheer terror.
I would love to see this kind of behaviour, much like LeftyRighty mentioned, it would add some depth to the squad management.
I don't really care if it would be distance-based (I mean, the soldiers are carrying radio headsets, right?) or fixed, but I'd like it to be there.
And what it comes to RL-ranks, I think we can bend those rules a bit. It doesn't need to be super-realistic to be fun. Unless, of course, there will be an option to choose between a "realistic rank system" and "this is a game fgs" when starting the game.
