[Predictions] Tobi son of sage of six paths

[joe256]

the sage's son is too old he wouldn't hold a grudge against konoha because when he was alive there was no konoha
there were many descendants after the sage's sons and probably other clans before they were called uchiha clan and senju clan

Its only natural that the elder son would hate the younger sons descendants which went on to topple his defendants into submission and from their created Konoha. Which might be why he used Madara name because he was just like him in failing to beat Hashirama. He said it himself history is repeating itself.

He harbors a grudge towards the descendants of his brother and what his descendants went on to create if that clears things up. Like Itachi said, he is a sore looser

Naruto himself is officially from the Uzumaki clan, but Tobi himself said he could sense the Senju inside of him.

There was also a gap between when Madara left the village after his own clan decided to make peace with the Senju and when he returned, I believe it was in that gap that he met Tobi( his ancestor ) and was taught how to control the 9 tails.

That would be plausible considering Madara seems like he knows who the masked man is, and the only way he could know that is if he met him before he died, but after he left his clan.