"This is the relevant section:
キャスト陣からヒナタの2人の子に関して「白眼」は？ と質問が飛ぶと「やろうと思ってたけど、忘れてました（笑）。（子どもが）3人になれば…。でも、そうなるといろいろ複雑になりそうで…」と苦笑していた。
(On mobile, so will have to give loose summary translation~)
Interviewer asks, "Why don't the two children have the byakugan?"
Kishimoto says, " Ah, I intended to, but I guess I forgot about it (laughs). If there's a third child, however, but then it seemingly will get complicated in various ways (laughs sarcastically).
("Though it was intended, I forgot about it (laugh)".)
So uh, no. Not really going to have another child. It's more like if he wants to fix the mild error and give the byakugan to one of their children, then he's going to have to ask NaruHina make another one lol~ (The hypothetical third child would then have it).
The tone of Kishimoto laughing here is more on the side of joking about correcting his oversight of how Boruto and Himawari didn't have the byakugan on accident. (And implies that they'd need a new kid for that
) I think the "it's complicated" part of his answer refers more likely to how the bloodline limit (/genetics work) for why the first two kids didn't win the genetic lottery of the byakugan... but how this hypothetical third child will. He would need to explain it~"
Credits: OrganicDinosaur on Reddit.
Edit: some kanji appear to not be working correctly...
