Before I start, to those that haven't seen the Nintendo Direct yet (http://www.nintendo....ive/01-23-2013/), you should do so!
Both new Zeldas sound awesome! After listening to Mr. Aonuma talk about the visual style of the new HD Zelda game, I just wanted to make sure I understood correctly:
It seems to me that Mr. Aonuma didn't necessarily say that both games are going to have the same artstyle (even if things turn out that way, I am totally fine with that for the record). I will explain how I came to this conclusion:
Mr. Aonuma started talking about the new HD Zelda and the different experiments he and his Zelda team have done for the visual style of the game. The E3 2011 Zelda tech demo for Wii U, the video the Zelda team called the Zelda HD Experience, was one example of their experiments:
With that in mind, lets rewind a bit. He started off by talking about rethinking the conventions of Zelda for the new Zelda in HD, then after that, he changed gears by saying: "Separately from that,...". He then talks about the different artstyles they have redone in HD from past Zelda games as experiments for finding a visual style for the new HD Zelda. The images he shares with us next "have emerged from the development process for this new Wii U game...". Notice all the images he presents are from The Legend of Zelda: The Wind Waker. Interesting...maybe he is going to say next that this visual style was decided upon for the new HD Zelda. After all, they "have emerged from the development process for this new Wii U game...". Instead he mentions the reasons for showing us the pictures.
Continuing my quoting directly from Mr. Aonuma from the Nintendo Direct presentation: "The reason I wanted to show you these pictures today is because our new Zelda title looks like it is going to take some time to complete..."
So far this either means pictures from the new HD Zelda or something else.
Continuing the quote: "...so I wanted to report that while you're waiting for that game to release we intend to offer you The Legend of Zelda: The Wind Waker, reborn on Wii U, to play in the meantime."
Put emphasis on the word so in the above quote and the whole thing reads like this: "The reason I wanted to show you these pictures today is because our new Zelda title looks like it is going to take some time to complete so I wanted to report that while you're waiting for that game to release we intend to offer you The Legend of Zelda: The Wind Waker, reborn on Wii U, to play in the meantime."
Interesting, so the first listen through, one might think Mr. Aonuma is saying the artstyle presented is going to be for both announced Zelda games, but upon a second listen, at least to me, it sounds like only one will have this artstyle (at least for now).
Whether this is a misunderstanding because of the language barriers I do not know, but it is interesting nonethaless.
This means that the E3 2011 Zelda tech demo or the Zelda HD Experience is still a possibility. Who knows what further experiments might lead to.
If I missed anything, or if you think you might have found an error in my analyzing of Mr. Aonuma's presentation, please do share. I am just speculating as an excited fan.
Also, feel free to add to this speculation thread over time with your input. Everyone's input is greatly appreciated.

Take care everyone!
Sincerely, NintendoFan