While not specifically from Firefall, unless you count smokescreen and remote explosive, I'd like to see some stealth/subtle abilities to help flesh out something more akin to an assassin/sharpshooter class built for harassment and strategy rather then raw firepower or buffs which dominated the nighthawk/raptor gameplay.
Things like short term
stealth fields,
remote/proximity mines, maybe even a large area
'mini-nuke' with a long activation time for area denial or removing entrenched/slow enemies.
If picking up your own loot is a thing, please have some pity on the long range snipers and give us a way to pick up at least some loot (not necessarily all) from range. Maybe a little mech that you can call in that will temporarily scrounge around the battlefield to retrieve stuff far away from you if you laser paint the item/area or something. Bonus points if its weaponized, with a small explosion at the end of its life, that you can use as either AoE or kamikaze fashion by painting an enemy target instead of an item ^_^
Also, yes, turrets were fun thumping, but way OP. Early on, In most areas, you could literally
solo a P3 thumper completely afk and no where near the area with little loss on your turrets.