retro themselves confirmed the absence of kremlings and underwater levels
Regarding the Kremlings' supposed "absence"... I still think that there's a slight chance that King K. Rool may very well be the true mastermind behind the events of that game. Usually, no other villain is interested in Donkey Kong's banana hoard but him, and I highly doubt that anyone else would steal it if K. Rool wasn't behind it in some way, shape, or form. Sure, Retro Studios might have claimed that he wasn't in the game, but even "official" statements from the PR could turn out to be false.
For example, before Star Fox Adventures was released, a Nintendo and/or Rare employee claimed Falco was going to be absent from the game, but he ended up making an appearance later on in the game (and a rather important one, too). Also, last year, Cammie Dunaway or some other Nintendo representative claimed that there was going to be a "new final boss" in the New Play Control! version of Donkey Kong Jungle Beat, and that turned out to be false. Lastly, the official Nintendo U.K. magazine
claimed that Sonic the Hedgehog was a playble character in Super Mario Galaxy 2, along with a hidden "Green Hill Galaxy" stage, and that turned out to be false, as well.
and there's nothing on the DK crew and animal buddies as of yet
Yeah, you're right about no Animal Buddies being shown in the trailer, but Retro Studios assured the fans that there's still a lot they have in store for the fanbase, and I'm pretty sure that's going to be one of them, along with the return of the supporting Kong cast.