Just because Capcom shipped 2m doesn't mean it's had to of sold 2m yet - it could just merely be that retailers are strapped for DMC4 copies, and have massively re-ordered lots of new copies.
Having said that, that's great news for Capcom, and their next-generation games. Capcom projected only 1.9m units to me sold of DMC4. It's already shipped that many in 3 weeks, which is phenominal.
With sales like that, RE5 might stay PS3/X360 exclusive.
Back from the dead, I'm afraid.