I have no clue. The manga would have completely changed though. I believe Kishi said he had the idea of akatsuki for a while so that wouldn't have changed. But the addition of Itachi made him switch from them being monsters to just regular humans (if I am not mistaken, it was in one of the databooks)
Sasuke was a fantastic addition to the series, great rival and fits the role of avenger perfectly in my eyes. He gets annoying sometimes, but I'm glad he was added
Edit: But Sasuke's conception was created before the first chapter was published. Along with Hinata, Sakura, Kakashi, and Iruka. So, the pilot would have probably been different too, but the beginning wouldn't changed all that much
