I do think that we will get a Zelda release for the Switch this year. I suspect that it will be a remake.
Skyward Sword HD seems the most logical, because this game does not have a remake yet but really needs one. The game was released at a time that the Wii has lost its popularity. For me, I was getting fed up by the "motion control" hype and I will probably not be alone. A remake that can be played with the Switch Pro controller, one of the best controllers ever, would be very welcoming. Also, do not get started about the poor graphics of the Wii...
However, the remakes that have been released for Wii U probably did not sell a lot of copies because, well, not so many people have a Wii U. So it is also possible that Nintendo decides to re-release these remakes on Switch.
I do not expect a completely new game somewhere this year. And I really, really hope that there will not be a mobile Zelda game...