Basically what the title says When Obito went back to Madara after slaying those Mist Nins and unlocking his Mangekyou, would he of survived the Uchiha Massacre had he abandoned the plan and went back to the leaf?
But he caused the Massacre :| Without him = no Massacre xd
Unless you mean when Root would of killed them .. then I'd say maybe as long as he had MS and had good training xd
1. The whole plot will completely changed, itachi's new order would be along with obito will hafta go after madara.
2. Madara will himself killed both of them