Itachi was always and will always be Sasuke's entire world. Call it sick, demented. But as he lay next to Itachi's corpse, it's implied he was slowly dying, and he simply did not care. I believe that if no one came for him, he would have died a long side Itachi. As with the clan.. he also did not seem to care about them.. as much as he cared that Itachi abandoned him in such a brutal fashion. It's either an intense bond between brothers, or something much darker, deeper, emotional. Although Sasuke has in the past had emotional connections, his primary connection was to Uzumaki Naruto- and even then, there was a great distance. In Sasuke's poor tormented mind, I do see that he perhaps adores his brother more than he should. As with Itachi.. I believe that adoration is mutual. Basically, because of the intense trauma both have endured throughout their lives, it's made them both mentally ill in some shape form or fashion. So.. my answer.. would have to be.. He simply doesn't care about the light. His life's only meaning is gone, so what would you do in his situation? Receive a hug from Naruto and it would simply be water under the bridge? Unless Itachi's power within Naruto has some way to bring him into the light, Sasuke is damned.