I doubt the game will really care which direction you swing the remote in, it would be a lot more extra work to have Link swing his sword the same way you swing the remote, so he'll probably swing it normally no matter how you swing the remote.
I just hope they remember to go into the dialogue and stuff, and change directions accordingly. I doubt level designers took the fact that Link is left handed into account, it really doesn't affect the game that much. Sure he swings his sword in a slightly different direction, whatever it's 3D so just just turn counter-clockwise a bit and you'll be aiming at the same spot as if you had been left handed. Also since it's 3D it should be interactive enough for the player to be able to adjust to the slightly different game dynamics. The only problem I really see mirroring Link is that his animations may not line up with other things properly, and at this point in the games production It's a lot easier to flip the whole world then to redo every animation again. I mean, basically you just have to flip the image on the screen and the controlls (drawing the HUD correctly after flipping the view), also any textures that have writing on them.
I find it silly that they changed Link to being right-handed. It does make sense so that the player doesn't feel odd that the character is swinging his sword the opposite way they're swinging the controller though... poor left handed people.