The fight wont end before Sasuke uses the curse seal.

I'm with the others that it might not have been Sasuke that screamed at the end...
Then again....it definitely seems even more out of character for Itachi to be screaming.

Who knows?

Edit: Actually I know...
It was Zetsu who screamed, because Sasuke used a genjutsu to make Itachi think that Zetsu was Sasuke.