I actually read that NaruSaku WAS supposed to happen. A guy I've been talking with on Fanfiction said he found some of the original artwork or something along those lines. He's looking for the source again, so I'll try and get it linked soon.
If Kishi were to come out and say "Yes, NaruSaku was supposed to happen" then it would be NH/SS worst nightmare come true. Part of me has to believe that he was just put under pressure. He was surrounded by NH fans, and it wouldn't have been a fun time for him if he'd made NS the final pairing. Heck, maybe they wouldn't have even let him publish the final chapter if he didn't make it NH and SS
That reminds me to old times when someone in Tumblr said that the person saw final poster that hadn't been released yet in a shop and it showed NS in it, under sakura tree, if I'm not mistaken. Then that happened and the poster seemed to be taken, gone from the shop.