The present Sky tactic of 'ride tempo to 1km to go, don't break it even if others attack, then and only then does leader launch his only attack of the day' worked a treat at P-N and T-A.
It's really difficult to see how it can be matched just now, unless other teams work in the same way. If Contador and Nibali had not gone on the attack themselves, they might have had the legs to stay with a fresh Froome. Doesn't matter who the domestique is, Sky have got a range of guys who can sit on the front, ride to their threshold then drop off to come in way down the order, be it Suitsou, Lopez, Cataldo, Kiryenka, Kennaugh, Henao, Porte or Uran, or Boswell, or Dombrowski... it goes on. Wiggins in the Tour this year as well? He did it in Oman. The depth of climbing talent the have is frightening and they don't have to worry about where these guys come in so there's no issue of conserving energy for the dash to the line.
Horner was probably the canniest rider yesterday - he hitched a lift on the back of the train and bridged with Froome across to the 3 leaders.
To beat Sky riders have to keep their cards as close to their chest as possible, either by riding in their own train on the front (which requires a hell of a lot of work in training) or restricting attacks to save energy. Froome himself has said he kept himself fresh until all the others had made their failed attacks.