What he said, well some of it...
Madara and Tobi had this plan formed before Itachi was even born...
Nagato is older than Itachi, and it was said Madara gave Nagato his Rinnegan...
If Edo Madara didn't show up, i'd say that he wouldn't move to that part before getting is revenge on his clan... Then again what we now call fake Madara, or Tobi can be lying like it was his last day on earth...
Now, knowing that Tobi is not what we think... i guess he would try it anyway.
Unless the Sharingan is an hindrance to his plan, and then he'd have to kill the Uchiha..