What if Itachi was the younger brother and Sasuke was the elder brother?

[USSJ Future Trunks]

without itachi torturing him and orochimaru's temptation, sasuke would be a very heroic, reasonable and kind person and brother.
he'd rise to the top of uchiha clan and convince them to not rebel.
with indra's influence, and his natural aggression thanks to trauma as a 4 year old, itachi would join anbu and be danzo's most loyal buttboy.

ouldn't become a pacifist=no motivation to better himself.

no uchiha was ever a pacifist.