1: 1st theory is that Kishi will make Naruto's BM fail in the 1st panel of the next manga, cause he's a funny dude.
2: I think this is the moment we've been waiting for, Naruto achieving perfect BM and being able to control it longer than before. Remember last time he used a huge amount of chakra to make a Biju-Dama capable of taking out 5 Biju-Dama's, this time, he might not need to use that sort of power.
Lastly, I think that Naruto is perhaps going to reveal whatever it is he got from those other Biju, and also maybe start using his own speed to outdo Tobi's space time ninjutsu.