I could see this happening, too. If Mario is ready and Skyrim really is launching with the Switch that would make more sense as a launch line-up than launching two huge open-world titles at the same time.
I agree Zelda and Skyrim releasing at launch would be a bit too much. I expect Skyrim to launch a month after with extra features such as Zelda themed dungeon and access to Shield and Master Sword. So Bethesda adding these features may take a while and would allow Zelda release to hype up their extra Zelda themed content in Skyrim.
I expect something like this for launch
Zelda - Open world Action RPG
Monster Hunter XX - Action Monster Slaying game
Dragon Quest Builders - Minecraft type game
Tekken 7 - Fighting game
Mario 3D World port - Platformer
NBA 2K17 - Sports Game
Borderlands Handsome Collection - FPS
The above line up has most genres covered. Appeals to Japanese gamers as well as the west. Mario Kart and Splatoon as well as Smash Bros and Skyrim will all come out in the same year with new content. Super Mario 128 will be the big christmas game and Nintendo will also have new Pikmin 4 games well as Retro New IP coming in 2017 for fully packed lineup in 2017.