As we know the requirement to unlocking Susano is to master both Mangekyou sharingan, it seems once that requirement is met then Susano can be unlocked and be permanently unlocked even if the user loses his eye.
Itachi mastered both his eyes = can unlock Susano and even when he goes blind doesn't lose it
Madara don't know his mangekyou sharingan skills, but unlocked Susano = Once Madara unlocked Susano even when he loses his eye he still keeps Susano
Kakashi mastered 1 mangekyou sharingan, he saw all the ability of the other mangekyou sharingan by battling Obito = Kakashi unlocked Susano with the temporary sharingan, even if Kakashi loses his sharingan, Susano is now a part of him, like Itachi and Madara, remember Obito never used Susano, Kakashi was first one
There nothing in the manga that mention you have to be an Uchiha to gain Susano.
Itachi mastered both his eyes = can unlock Susano and even when he goes blind doesn't lose it
Madara don't know his mangekyou sharingan skills, but unlocked Susano = Once Madara unlocked Susano even when he loses his eye he still keeps Susano
Kakashi mastered 1 mangekyou sharingan, he saw all the ability of the other mangekyou sharingan by battling Obito = Kakashi unlocked Susano with the temporary sharingan, even if Kakashi loses his sharingan, Susano is now a part of him, like Itachi and Madara, remember Obito never used Susano, Kakashi was first one
There nothing in the manga that mention you have to be an Uchiha to gain Susano.