Can you imagine tactical simulator without military specialisations? Yes, you can. It's XCOM: UFO Defence.
Guys, common! It's year 2014.
We must have
1. Sniper (operative with fine accuracy and,
WOW!, a Sniper Rifle!
SVD or AWP.
2. Support (operative with LMG-MMG (like M60 or PKM) and tons of cartriges.
3. Assault (operative with Assault Rifle like AKM (AK-47) or FN FAL).
4. Medic (operative will treat wounded soldiers).
AND
5. <insert Your terminator here>
We don't need even "classes" like Battlefield or Baldurs Gate. Just apropriate weapons and equipment. Just like Jagged Alliance games did.