User blog comment:PresidentEden78/DICE details pre-order bonus lineup for Battlefield 3 and Open Beta FAQ/@comment-99.138.92.222-20110805073125

Why the hell would DICE go back to two factions? BF2 had three in the base game and an additional seven in the boosters.

Unless DICE plans to follow suit with BF3, adding more as DLC in the future. Maybe the Back to Karkand expansion could offer the MEC?