Possibly related to Orochimaru and Kabuto's research into the Rinnegan. Didn't Suigetsu comment in shock at how far Orochimaru had gotten? Maybe there's something beyond the Rinnegan like the 9-tomoe Rinnegan, lol. Though is a Sasuke power up enough to affect the 4th Great Ninja War...? Idk :shrug:
IWR/ET is going to get shut down by the Uchiha brothers it appears, so I don't think it'll be that. Albeit it could have something to do with Fuuinjutsu or genetic manipulation...; however, they're not really Sasuke's style... I really can't say, given how little info we were given.
I do think it will lead to an Uchiha Sasuke power up though... Thus, I think it has to do with doujutsu research as my top
guess. They really didn't give us much info. On purpose, of course, lol.
Peace