It's very funny to see that fans really believed that this wasn't Link to begin with. Was the chance of it being a different character? Maybe about 1-10%, but I personally believe that it was Link from the start and simply Mr. Aonuma was having fun toying with the fans. It's great to see that
Mr. Aonuma does have a sense of humor.
Honestly I find it dumb that fans automatically believe that just because Link doesn't wear his green tunic and hat doesn't make him any less of him. We saw Link in blue garments when the screenshots of Hyrule Warriors came out just a few weeks ago people! Wind Waker, Twilight Princess, Spirit Tracks, and Skyward Sword all featured him at one point without the green tunic, that doesn't make him any less of himself.
In the end, I'm glad that people can rest assure that it was Link we saw in the trailer. I do hope we can some more footage within the next few months when the game has had time to develop more.