On the long run, it might help. However, it would cause a lot of confusion when first implemented, and be a huge excuse for "accidental" teamhits.
Issues: That enemy waiting to ambush you just behind that low wall? Well, he is useless now. And a few other things (archery in the distance would be a bit easier, etc. Not sure if I like it
Also, can you see banners through the fog? Cannot remember atm, but if you can, even if just at a slightly bigger distance than you can see players, it would be a big advantage