I am very familiar with trails bikes and why a disc sticking off the side of the bike is completely unworkable. Hydraulic rims brakes is the best choice for a trails application.

We aren't talking about trails bikes here, are we?

Roll of eyes...

Also, rim construction on a trails specific rim vs a road race rim is VERY different. I am willing to bet that a hydraulic rim brake would crush those cheap carbon clinchers being dumped on EBay...

If anything it means Sram has developed the shifter for hydraulic discs but the calipers aren't ready yet and they are rushing the shifters to market so they don't get bludgeoned by Shimano and Campagnolo (to a much lesser degree) in 2013.