Guys guys.
First let me explain something about Naruto's children.
They are the first of their kind because of the current Naruto breeding history: A powerful doujutsu clan (Hyuuga) has never mated with a powerful body clan (Uzumaki - Blood related to the Senju, distant cousins)
So therefore, whether these kids have a mutated version of the Byakugan where the white hue does not have to be apparent in the form of a doujutsu is unclear. They are 'freaks of nature' unlike Tsunade who comes from an Uzumaki/Senju (Both have powerful bodies) linage in her grandparents blood. Naruto and Hinata are way different.
Therefore the possability of these two having the Byakugan is 50%. We can only know until part 3.
Mating season.
"Byakugan is 50%" - is not correct.
The degree of having bloodline is never 50% - 50%
Hagoromo elder son has nearly fully Hagoromo bloodline, but younger son was not at all.
There are trade-off, either mostly the father features, or mostly the mother feature, or even none.
Naruto has much higher percentage of his father feature, but not much on his mother feature.
Naruto having more stamina may not come from his mother, but from Kurama as Minato seal will leak Kurama chakra and merged into Naruto chakra. Also about Minato FTG, Naruto did not have at all, but thanks to Kurama power (Chunin exam).
It is only when Hagoromo gave him his power to Naruto only, Naruto speed is enhanced (Sasuke did have).
btw. The possibility of
both children of Naruto & Hinata, will activate their Byakugan (similar to sharingan eye).