I really don't think its a realistic vision. Ask any landscape architects and they will tell you having trees on skyscrapers is pretty crazy.
It does seem a bit gimmicky. I would like to see the building when the leaves are changing colors, that could be beautiful. sounds_sound, what do you make of it?
Hmm. Doesn't seem so crazy to me. Gimmicky? Not sure. As gimmicky as any other rendering of a building is I guess. There isn't anything technically impossible with this kind of building. Concrete is way stronger than it used to be even 20 years ago and can even be made waterproof now. Conceptually though, this is pretty well worn territory. Basically as early as people could even imagine something as silly as the words "sky" and "scraper" being put together, there were already trees in them - well at least in their drawings.