One of the reasons Pixar is so committed to short films is because they can use them to experiment with things technically. One of the reasons they made "The Blue Umbrella" was to play with the notion of photo-realism mixed with the hyper-cartoonish. The rain and the cityscapes in that short look like they're real, and then the faces we see on the umbrellas are so simple, so cartoon expressive.
Now it looks like we're seeing the payoff from that experiment with their next feature, "The Good Dinosaur." The opening moments of the trailer almost appear to be live-action with the rain and the plants and that tiny lizard thing. And then we see Arlo's foot enter the frame, and immediately, we're looking at something that is even more cartoonish than Pixar's typical design work. To some degree, it feels like a big stylistic jump for them, but one that has evolved out of the work they've done in the past.