Actually the way Sasuke is going Uchiha Clan wont get their reputation back.
1. None knows the truth of the Uchiha Massacre.
2. People knows Itachi as a evil person who massacred his clan to test his powers.
3. If Sasuke 'crushes' leaf people will know him as another mass murderer.
4. Tobi is recognized as a uchiha who began the Fourth Shinobi war.
5. A revived Madara Uchiha is fighting against the allied forces.
So Uchiha Clan wont get its reputation back if Sasuke commits another mass murder. But instead if helps the allied forces and then forces the elders to confess their crimes in public and then kill them, Sasuke will be hailed as a hero.
BTW If Uchiha married only the Uchiha in the first place that wld be little incestuous. They have married outside the clan and the devolution of Elder son's eyes is the proof of it. Also the ability of Sharingan to develop to Rinnegan also proves the power of the eye wont be lost as long as someone bears the slightest bit of Elder son's blood.