I think the Uchiha WAS planning some kind of rebellion. When you think about what Itachi's dad was saying to him. They were having a meeting that was more important that Itachi's ANBU mission, and from the way he described Itachi as their pipeline to Konoha, it wouldn't surprise me if the Uchiha were using him to spy on Konoha just like Konoha was using him against the Uchiha.