Since we're all predicting what will happen...

Sasuke defeating Itachi will have to be towards the very end of the series since that's his dream (like naruto's dream) Sasuke's end will be he defeats his brother then he doesn't kill him just to prove he's better than his brother (I beat your ass, but your too pathetic to even waste my time killing) and his brother will probably kill himself and say something like I'm proud of you, or I'm so sorry or something right as he dies.

Either that will happen, or the equally dramatic not so happy ending of Sasuke killing Itachi then becoming evil (Thx to Orochimaru) and Naruto and Sasuke fighting each other to the death in the last episode. Naurally Naruto wins and Sasuke dies in a very sad way as he says he's sorry to Naruto and that's he's finally free to join the rest of his clan...

But that's just my prediction [img]i/expressions/face-icon-small-tongue.gif[/img]