I doubt all is in vain. Sasuke turning new leaf at the time being doesn't necessarily means everything is going to be as it is supposed to. Madara seems to turn on new leaf when everything start to take an abrupt change. The thing is, no one can really foretell how it is going to be. One good thing that we can take from current predicament is that nothing is holding Naruto path to become a Hokage. Suppose things start to go south once he became a Hokage, things will still look goods - In a sense that Naruto does not betray all the promise he spouted to Neji, his mom, his dad etc...
Suppose the final fight between Naruto and Sasuke indeed results in both of them dying, Naruto not becoming a Hokage in turn reflect on his failure to kept his promise to others. On the other hand, suppose he became a Hokage while sasuke is still in the path of revenge, he had renegated on his words that 'how he could become a hokage if he couldn't even save a friend'...aren't his ninja way suppose to be not going against his own word...
Lastly, suppose sasuke has indeed change his ideology that doesn't means his past crime can be simply overlooked. Surely contempt among who he had inflicted damages to remains. Even those among konoha there are some who might not truly accept his redemption. From an uchiha elite he might be a pariah among the villagers. As such the idea to re-built his clans might in some way prove to difficult a task that further conflict might ensue.
I guess I rambled to long and I'm quite lazy to check what I have written...so hope it does convey what I meant to say...
