I mean the Shin has the blood of the Uchiha in their, they even have the Mangekyou Sharingan which is still a huge feat within the Uchiha.
Heck just unlocking the Sharingan is a huge feat by itself, but reaching Mangekyou Sharingan is even bigger. When those Shin have kids that means even more Uchiha with Sharingans in the future.
So the bloodline for Sharingan will not go extinct like Kimimaru clan, which Kimimaru was stated to be the last of his clan.
Heck just unlocking the Sharingan is a huge feat by itself, but reaching Mangekyou Sharingan is even bigger. When those Shin have kids that means even more Uchiha with Sharingans in the future.
So the bloodline for Sharingan will not go extinct like Kimimaru clan, which Kimimaru was stated to be the last of his clan.