I'll go out on a limb and try to predict the exact way tomorrow will play out. (This is why I think the Tour is boring)
It's a short stage so there will be huge pressure for a break to go, and eventually one will be established which contains enough no-hopers that it finally gets the Peloton to slow down, but then they get a huge advantage, like 10 minutes.
Then, everyone will look to Astana to drive the bus. In so doing, they will run their guys ragged but not gain back much time on the break. Aru will sit on for most of the stage. Astana sets a tempo which does no damage to the Sky guys by the top of the final climb. Bardet attacks the final descent, gets reeled in on the runout to the line. Winner is out of the break which still have four minutes. The remaining GC contenders all finish together, looking at eachother and their teammates. A fairly large finishing group.