I have a feeling that he will continue on with his revenge, possibly to Madara. It is also possible that he will feel the internal/emotional pain that Kakashi was referring to, though this may also occur at a later time. But most of his time will be invested into preparing for his match for Madara. I don't think he will be joining forces with Naruto quite yet.
I think it depends on how the fight will end. You cant expect him to act the same way if it ends with him being
b) half blind
c) reunited with Itachi (i know, i know, my "reality" sucks)
e) saved by someone else
I think was Kishie wants us to think that he'll do is that he'll kill itachi and go for madara, but there's just too much action around.
I mean, I think we left Naruto (and some leafs) fighting Tobi and Kisame with Hebi. Anyway, at some point he'll meet with both Naruto and Madara -case he survives for which i'm sure, i mean, its jump!
Would totaly ruin the excitement if Sasuke managed to kill itachi, hopefully Sasuke will walk away blind or something similar. Atleast thats what i hope for, would strongen the storyline, and make it more intresting for the readers.
Him walking away as a winner would just.. blow.