I think a lot would change. Access to the Sith Holocrons would give Anakin hope to save Padme, so he wouldn't fall to the Dark Side. Mace Windu could have arrested Palpatine if Anakin hadn't intervened and sent him flying through the window. Order 66 would never have happened then because Palpatine's dead, and Padme would give a healthy birth to the twins, Luke and Leia would be trained at the Temple by Yoda and the rest of the Jedi, and everybody lives happily ever after.