I don't think games will ever be designed with dual GPU's in mind. This card is really the same as 2 3870's in crossfire, a multi GPU technology that has been around for a while just like SLi has. They've had plenty of time to start designing games around two or more cards and in most cases, that hasn't happened yet. While a lot of games do support multiple GPU's, developers can not count on everyone being high end enough to have that kind of system so games are still designed to be played on a single GPU, and if you have more than just one card, then the more power to you.
It's up to nvidia and AMD to continue to improve their drivers and increase the performance of multi GPU systems. Crossfire already scales very well, but SLI still has a long way to go before it is equally efficient.