Not necessarily. It's quite possible to discern friend or foe only by the way they move. Additionally, you have the name popup for friendlies.
Try it for a day, it's actually quite fun.
Yeah but you said "Also" as in you're also adding the "remove teamchat and the namebar" to your suggestion.
This would make it so every round start, you'd have to memorize every single gear loadout your team has to not teamkill and if anyone on the opposite team uses the same gear, then tough shit differentiating.
Though, if nameplates are kept, I would definitely like that.
I just find the idea of banner retarded, I personally always wanted both teams to just have different uniforms, like keep armors as is but make them colored depending on the player's respective team, so if you're on the green team, everyone's armor has green to it, if you're on the white team, everyone's armor has white to it, etc.
It would actually make me teamwound much less, there's so many times where I end up killing a teammate because his white banner is on a white snow background, so I just don't see it at all.