That 3D Kirby mini-game looks interesting but I hope it isn't what a full 3D Kirby game would be like.
Like it looks fine for a mini-game since they're just testing things out, but I would much prefer something akin to Super Mario 64 or Spyro the Dragon in terms of how the levels are designed if we get a full game (Kirby Air Ride kinda teases it with City Trial). I think having an open 3D environment, with rolling hills and dynamic geometry and all that, would be a much better showcase of Kirby in 3D then if they made a full game with static and blocky environments like this mini-game. Because right now, it just looks like the original Kirby game with an extra 4 directions to walk in. Adding copy abilities to that wouldn't make it much more interesting. If anything, I think it would make the already easy Kirby games, even easier, since at least 2D spaces can be more easily compact and crammed with intelligent obstacles for Kirby.
Just my two cents. I'm looking forward to the mini-game and I hope it has a decent amount of levels, but I hope it's just them showing off the vaguest idea of "3D Kirby", rather than "this is exactly the kind of gameplay and level design we would use for a 3D Kirby game".