Because Porte has often climbed with the elite, I suspect he and his DSs assume that he's always going to be a GT contender, much like Majka or Mollema. Talent-wise, yes, he's for sure capable of a GT podium and winning almost any weeklong race, but I wonder if he should think carefully about what he wants to accomplish in the last 2-3 years of his career. Going back to Sky as a dom would be a pure money move, and maybe that's OK, but I'd still like to believe he has more wins in him.
Sure, he might have left Sky one year earlier but IMO a bigger blow was the dissolution of BMC.