I would imagine that Sky’s tactics will be to keep trying to chip away at Nibali, or at least keep in touch, so that Porte maintains his podium place, with the possibility that Nibali could always have a bad day and open the door for Porte. And there’s still the ITT to come – who knows, Nibali could crack, or fall off. It’s a bike race, so anything could happen (cf. Cav, Froome, Contador, Talansky etc).