3 Sivan (Korach)

Rashi Bamidbar 16,7 says that Moshe said that only one from korach and his followers will live and korach misunderstood and thought that he would be that one that lives because he saw all the great people who would come from him. However he made a mistake because actually Moshe saw that it was his sons who would do Teshuva and were therefore saved and the great people that came from him were able to come from him through his sons. How does it make any sense that Moshe says ONE person would be saved and Moshe saw that Korach's SONS (plural) would be saved? If Moshe saw that his sons would be saved why did he only say that one person would be saved?
It doesn't make sense to answer that that person who would be saved was Aharon (and the one person who would be saved also includes the ability for it to be Aharon and Moshe wasn't just talking about one person from Korach and his followers) and Korach's sons weren't included in the fight at all, because then you would have to say that Korach figured that there was some reason that Korach would hold that for some reason Aharon deserved to die. However there is no logic to such a reason and Korach never says anything remotely simaler to that which would even imply he thinks anything at all like that.