If you wanna be politically incorrect: Basically throw Kira under the bus (turn around in that same game, and make up for it in a different way, so not to anger fans) and Glorify Shinn.
Politically Correct speaking: Have shinn make better choices. Have him react different to situations, and the people around him. Trully become Kamille of the new era. And if there is something I missed, please feel free to add.
Only problem I have with this, is that it comes off as them playing God (and I don't know about that). They act like they have the script from Destiny, where shinn turns out differently then it's Counerpart. I don't care how good/bad someone's work is, you don't toy with someone's story, just cause you think you can write something better (not with that kind of mentality at least). Acting like they got the Original script of how Shinn was supposed to turnout, and the game is just their meduim of getting it out there. It's really just the equivalent of a FanFic.
Pretty much it.
