Aha, Shimano saw this thread, and relented. From Bike Radar:
Shimano Ultegra 6800 mechanical groupset - first look
The new Ultegra chainset gains the four-arm design that's proven itself with Dura-Ace applications – it's lighter but with the same stiffness as before. Options will be 53x39T, 52x36T, 50x34T or 46-36T, with a triple in the pipeline for later release.