Sakura's Byakugou requires precise chakra control, like you said if Hinata can close up her points like most other shinobi she'll lose. The only reason why Naruto won was because the Kyuubi was a completely outside source of chakra, it wasn't connected at all to Naruto's chakra system. So if your chakra points are shut down, they're shut down and you can't use any chakra, which is why the Byakugou would also get shut down.
With that being said, I still don't think Hinata could beat Sakura. Sakura is fast, plus she could defend well with punching through the ground to keep distance. Also, Hinata cannot deal with Katsuyu. Katsuyu obviously provides a ton of offensive support for Sakura, plus if Sakura does get hit Katsuyu could probably help bail her out.
It takes more than one hit to shut down an entire chakra system, and I don't think Hinata has the speed or abilty to land said hits. Plus, Sakura is almost as dangerous as Hinata at close range, one hit probably could take Hinata out completely. And of course, as I said before Katsuyu is impossible for Hinata to deal with.