I've accepted it long ago, but I still hope we're going to get a realistic ending, not a fairytale ending.
Unfortunately, I have to agree with Sasuke's essentially certain redemption. I have no idea how Naruto is suddenly going to reach him and affect Sasuke's heart, but somehow he will.
Maybe it won't be a goody-goody dream of bliss, though. Maybe Sasuke will conclude -- based on his own supreme wisdom, of course -- that Naruto is right. Maybe Sasuke will be bested by Naruto and simply agree to quit fighting, then wander off with Taka and Orochimaru to seek their fortune elsewhere.
I don't know. I just don't get what the movie will be about if Naruto solves every problem in his world. Maybe what will be open-ended is whether or not Sasuke will truly let go of his revenge over time, or if it will be left as a vaguely unresolved issue.
I'm really curious, too, about the bandage on Naruto's hand in the sketches for the new movie. Do he and Sasuke collaborate one last time and then the rift is permanently closed or something? Like... the seals on their hands are burns that never heal or something?
In a world as fantastical as this one, and with an author willing to cut the corners of believability even within that world, anything is possible without having to make a ton of sense.