Hmm, I know Tsunade's age would make it harder to impregnate her, but what are the odds that Boruto got her pregnant, which Naruto has to unknowingly support. Then again, some drunk sex is right up her alley.
Potential Sequels: Boruto goes back and has sex with Hinata/Sakura, changing the future.
OR
We continue with Naruto and Tsunade having a sexual relationship. She helps him notice Hinata earlier, and even convinces Sakura to take the blonde for a ride. Thus, Boruto unintentionally creates a harem timeline a la DBZ Trunks time travel shenanigans.