Should be at the very least a very scenic stage. I was up there riding about a month and a half ago and it was beautiful.
Never ridden up San Marcos Pass but I've driven it and it's a pretty decent climb; it'll be a nice launch pad for the break. I'm surprised then didn't give Foxen Canyon (the second rise after descending from San Marcos Pass peaking at about 75 km into the race) a Cat 4 climb rating. Those two should sap the break's legs.
Just before they hit Avila Beach, at about 5k to go, there are some rollers that might affect any forming lead out train.
I don't see any way Sagan doesn't win this one.