The stage looks brutal to me because of it's length and nearly constant climbing. I believe the peleton will split into at least two main groups by the midpoint of the race. Then it will get further strung out on the last climb. Sastre and Evans may try to attack on the last climb if they are up to it. But Sastre is probably the only one who could get much time on anyone. However, I think that it is more smart to just ride at least three or four mountain stages and let natural attrition even out the field. Evans and Sastre will probably be up into the top 10 after 2-3 mountain stages without doing anything special.
But look, Astana has six guys that can drive the pace of this stage fast enough to bury all but about 6-8 riders. So I don't even think that they need to try and win this stage. Astana will just set a blistering pace that few can follow and then depending on where riders are at in the last 10 kilometers of the race they will either hold it there or send AC,LA and LL up the last part of the climb to further distance themselves from the field.