I think the big question it comes down to is how IX will conclude and tie into the saga thematically. If Ben dies evil, what will the concluding message be for the overall saga? What if Ben is redeemed and lives?
And if he is redeemed, how will that be executed? I think we immediately think of Vader’s redemption and just seeing it as a repeat of that, but I Ben being redeemed doesn’t necessarily mean it will play out the same way it did for Vader.