Just wanna see how people would respond to this:
There is another survivor in the Uchiha Clan, who could it be, none other than NARUTO.
It could make somewhat sense, they never really gave him a clan, and when he was hated upon by everyone, the clan could have been like,"screw you" and sent him off.
As for activating the sharingan, he could just be like a late bloomer or some crap, sorta like Obito.
it would be sorta funny to see that happen