Just thought someone should look at the recent shock in 559 regarding edo tensei madara with all the info we have.
As much as I hate to say this, it appears that it's HIGHLY likely that Tobi is madara's brother,Izuna. Dispite this I still believe Madara HAS AND WILL PLAY A BIG ROLE AS A MAJOR VILLAIN IN THE STORY as I feel Tobi and Madara have made plans to reunite and take over the world.
The only other people I can tolerate Tobi being is the so6p older son because the motive is still there, putting aside how likely this is if you know what I mean. Also Tobi may well be a previous Uchiha clan leader before Madara and Izuna took over. Hell he could even be Nagato with that "I gave nagato the rinnegan" talk. Tobi could even be a someone shape shifted into some else, one of the unquie powers of the rinnegan that hasnt been revisted since Nagato used the technique with Kisame and Itachi. Important to note that this allows the shape shifed being to use bloodline limits.
When it comes to this matter there's one thing that must be constant about who Tobi is and thats MOTIVE for this actions. It has to be someone that hates the so6p's younger son(eg,senju), likes amassing power and wants to take over the world. Also it has to be someone wise meaning old to be as knowledgeable as Tobi has shown about matters that a clearly before everyones time in the current timeline.
Althought I'm not loving this plot twist, on the birght side at least we get to see Madara fight and his EMS. Which will shed some light on the Madara vs Hasihrama fight which is another MAJOR issue that needs to addressed by kishi 10 TIMES OVER lol.