There is no confirmation of a part 3 yet. However the information with the new movie says: " The Last: Naruto the movie is part of the larger “Naruto Shin Jidai Kaimaku Project” (Naruto’s New Era Opening Project), marking the 15th anniversary of the original manga." and "The movie that connects with the next generation begins to go beyond the original work - The Last: Naruto the Movie!"
This new era opening project could perhaps be a part 3? The movie already takes place in the future by a clearly older Naruto. I hope there is a part 3 though, that would be awesome. Part 3 could perhaps be about Naruto travelling around trying to achieve peace? I don't see how he is supposed to do that in a few chapters. Or maybe it deals with more mature problems such as social/economic divides within the nations? With the character designs, you can see bandages wrapped around Naruto's right hand indicating that he might still have his sun symbol. If that's the case, then he would still have his So6P powers and he would be OP as hell. So it would be hard for there to be a new stronger villain apart from Kaguya. Unless Sasuke turns 'bad' again as we still don't know his true motive, then it could be about naruto vs sasuke.
Kishimoto, will be leading the way as chief story supervisor of the film, developing an original story and character designs. So it will probably follow the plot and could perhaps be considered canon.
