Id add sarada's path may just be a healthy progression for the sharingan and be the only one the successfully unlock the rinne-sharingan without senju blood because if we compair traditional uchiha blood and senju its essentially yin and yang, while sarada has the sharingan but behaves like a senju with her demeanor
I think we are forgetting that the way sarada got her Mangekyo Sharingan wasnt the normal way as did anyone else. Her awakening was through love and not pain or hatred. Meaning the evolution is not strait forward. Its possible that the eternal Mangekyo Sharingan is a necessity due to the hatred rather than having a Mangekyo Sharingan itself. Even Sarada's Mangekyo Sharingan design is different in the sense that it is made depicts light rather than darkness and despair from its predecessors. Im not convinced she will go blind but one thing i do know is while both who attained it was via a sibling its possible it can be via any transplant too if the blindness is not a product of hatred
