Obito's Mangekyo Sharingan never lost its light despite the usual drawbacks. Obito survived being crushed by a boulder in a ...

Sasuke, for example, awakened his Sharingan after witnessing the death of his clan and Obito got his eyes due to his immense resolve to protect his teammates in the third great ninja war.

Sarada needs the Rinnegan if she wants to scale up to the stronger enemies in Boruto. She could obtain this power.