I think Zelda will go with a CG art style maybe a bit stylized like Puss In Boots (another Universal film), but still "looking" CGI with a touch of Studio Ghibli like Japanese influence. Lots of beautiful "nature" shots.
My other guess would be the film could start with Link as a child and then age him up. I also think something darker in tone than Harry Potter, but not quite as dark as the Lord of the Rings movies.
Just as Mario is heavily inspired by the games, I think you will see heavy influences from Ocarina of Time, Link to the Past, and especially BOTW/TOTK.