I wouldn't know. I avoided the actual spoilers by not watching the videos except the first. Anyway, I'm sure there's plenty the trailers didn't show. Anyway, are you going to cry if I'm telling you the next Zelda takes place in Hyrule? Personally, I didn't bat a eyelash when I encountered
for example in the game.
And fine, the green thing is slightly more spoilery.. But still, I haven't mentioned anything specific. You don't know what, how, where and when, or what interactions you're going to have. And that's the surprise.. The context. Not the fact that he shows up.