on paper, great idea. Maybe just let the player have a small logo that shows up on their helmet/on the back of their torso.
Unfortunately, from a technical perspective, I'm pretty sure this WOULDN'T work.
I imagine you got the idea for this from Minecraft multiplayer, where every player can easily have their own skin.
Sadly, however, there is a large difference to how graphics are handled in Minecraft and AoS. In Minecraft, every player is just the same body shape with their own custom texture layed over the geometry.
Ace of Spades, however, doesn't use textures, which I believe is why it runs so well on such old computers. Just have a look at the banner at the top of the forum. You see how the two soldiers are actually made of hundreds of tiny blocks? That's how the actual game works, too. Your soldier's face isn't a face texture on a cube, it's actually a 3-D grid of cubes that make a face. And as much as it pains me to say it, this 3-D cube isn't going to work well with custom skins.