Call of Duty: Modern Warfare 4 is nearing 400,000 copies sold on Steam already, and that’s well ahead of where last year’s Black Ops 7 stood at launch on Valve’s platform. This is according to Rhys Elliott of Alinea Analytics, who added that pre-sales on Steam alone work out to around $21 million in revenue. Elliott said Black Ops 7 managed to hit around 200,000 copies pre-sold on Steam by launch. Modern Warfare 4 has doubled that, and with two…