A few updates from Scott -
Here's video Disney shared -
Technically, that's not quite true: Pete did make a few live appearances, albeit very few and very brief. Here he is in a crowd of other characters (probably in 1983 or '84, given how huge Pluto's pupils are; it's also probably Disneyland, since I don't believe the big-pupiled Pluto ever appeared at WDW):
Actually, the only time I can ever recall seeing Pete was in one of those Disney ice shows, in particular this one from 1988, when they did a special ice show for Mickey's 60th birthday. Pete appears in a scene themed to "Steamboat Willie":
In any case, Disney Dan did a whole video in which he complains about the lack of appearances by Pete in the park (save for those two brief appearances I mentioned earlier):
Among other things, Dan seems baffled by how, in the above picture, Pete is actually shorter than Br'er Bear, when he should be about that same size, if not bigger. Incidentally, the costume just released bears a striking resemblance to this one made by a fan that Dan also shows off. Do you suppose Disney looked to this video for inspiration?
As for Mickey's new look, I don't think it's much compared to Tokyo's Toontown, where not just Mickey but all of the characters got special outfits (sorry I couldn't find a better one; images like that are hard to come by):
It doesn't even bear any of the traditional Mickey color scheme at all, save for a few spots of red here and there. At least the rest of his friends' alternate costume are based on their tradition color schemes (pink for Minnie, blue and yellow for Donald, green and orange for Goofy, etc.). For the sake of comparison, here is an image of Donald and Goofy in their special outfits found only in Tokyo: