I will not argue whether Sasuke is "good" or not, but I do not think that he will walk the path of Madara. We, and by extension Sasuke, have sat through chapters of Hashirama telling Sasuke things that happened in the past, and how they lead to the world they live in now. I don't want to think that Sasuke would be so ignorant as to hear Madara leaving because of his loss over the Hokage title, and then becoming an antagonist to the village. He has decided that he will protect the village and his brother's memory, and it would just be silly to follow the path of someone that failed, was defeated, and that they are currently trying to defeat.
As for Sasuke becoming Hokage, there are ways that this could happen. One is because of Naruto. If Naruto, the man that saved the village, and the man that is saving the world, says something to the extent of "I trust Sasuke, and he and I already have a deal that he is not to touch the village without defeating me, and I will not allow anyone else to touch Sasuke." The promise that Naruto and Sasuke made about fighting each other has bound them from taking action against or accepting interference from anyone else. Sasuke even stated as much when he killed the remaining Zetsu clones, saying "You are not a Konoha shinobi, so you are exempt from the deal *black magatama*"
Another factor are the elders themselves. Sasuke is privy to some incriminating information, collected from Orochimaru, Obito, and his brother, therefore blackmail is possible. They may sponsor him based solely on that.
What I personally took out of the Hokage competition was a sense of foreshadowing to a need for a new Hokage. This would mean that Tsunade might become a casualty of this war. The plot thickens.
