the thoughts are the next:
AMD claimed it's top videocards will be all multi-gpu. But todays 3780 X2 and 9800GX2 have troubles in games => they cannot be recommended as universal card for gamer.
So I suppose AMD has already solved microsluttering problems for its top HD4000, 5000, etc series, otherwise there's no sense to sell 4870X2 since everyone can buy GTX280 and forget of any trouble