Tyler and I argued recently about whether or not humans will be recognizably human in 500 years.
Let us assume that scientific progress continues. My view is that parents don't so much like "difference," unless it is very directly in their favor. Using technology, parents will select for children who are taller, smarter in the way that parents value, better looking, and perhaps also more loyal to their families. The people in the wealthy parts of the world will look more like models and movie stars, but they will be quite recognizable. These children may also be less creative and some of them will be less driven. It's a bit like the real estate market, where everyone wants their house to be special, but not too special, for purposes of resale or in this case mating and career prospects.
Assortative mating can increase the variance of appearance (and other characteristics), but a) assortative mating is not obviously a dominant effect, b) not necessarily doing much over the course of five hundred years, and c) future science is more likely to reverse the boost in variance than to support it. One short person could marry another short person, without having such short children because of genetic engineering.
People will in various ways be cyborgs, but more or less invisibly from the outside at least.
Dogs look different than they did five thousand years ago, but that is because humans controlled their breeding and opted for some extremes. How would they look today if the dogs themselves had been in charge of the process?