There could possibly be a new set of Sannin.
Even though Hanzo is already dead, since the original Sannin were so legendary, there could be a new group given the title of Sannin by the end of this war. They would need to possess a similar skill level and potential as Orochimaru, Jiraiya and Tsunade, though. They would also have to face off against an opponent that has a reputation for being unbeatable. Furthermore, they would likely need to be able to display their abilities as a team to get a team designation.
That being said, while it could happen, I don't really see anybody meeting those criteria. Obviously, there are a number of individuals that meet one or two of the above criteria, but there are very few teams in the series that demonstrate overall greatness. Instead, I see different people getting individual nicknames and titles much like Kakashi is the "Copy Ninja" and Minato was the "Yellow Flash."