I believe that if Sasuke has children they will have the ability to use the Sharingan, but the effectiveness will lessen and lessen with each generation. The Sharingan is a very good ability but it uses up too much chakra and cannot be used frequently. Even if the offspring can't master the Sharingan ability they will still have the Uchiha's abilities in fighting and such and with new blood mixed with the Uchiha's clan maybe a new more awesome ability will be formed. Because of this I say that the Uchiha clan is dead though because it will not be remaining pure Uchiha blood.