Starting some time in the next 10 years genetic testing will enable embryo selection that will start off the trend toward healthier, sexier, and smarter offspring. That trend will accelerate in the 2020s and 2030s. Therefore in the 2040s and beyond we (at least those of us who live long enough to get rejuvenation therapies that make us young again) will witness a trend toward higher attractiveness. People will become more perfect-looking and more able. Parents will generally want children capable of achieving more success. This will tend to select for intelligence, looks, height, stamina, and motivation. The choices made to get these desired traits will select against genetic diversity in the humans species.It is safe to say that this sort of speculation has been around since the 1960s, when the progress of DNA modification was first thought to have potential. I even remember encountering it in an Archie comic once.There are problems, of course, with this simplistic assessment of future evolution. First, traits such as "intelligence" are polygenic, and much is unknown about how intelligence forms. It has been, after all, only a short time since the Forkhead Box P2 gene was discovered that seems to help drive language capabilities. Other genes are pleiotropic, affecting a range of traits. How do you influence one and not others? Even sophisticated gene therapy has a hard time homing in on one trait, and that is if it is not pleiotropic or polygenic. Second, people are remarkably funny about what they want. In many polls, it has been found that the women that men find most attractive usually winds up not being the one they will marry.
It is possible that we might be able to decrease the genetic load of the population but even this will be slow. Many diseases, such as MS and Parkinsons, are post-reproductive and their genetic basis is still largely a mystery. All of these factors (and others I am sure) have largely been responsible for the fact that humans don't look appreciably sexier, aren't healthier and don't have more motivation than their precursors 50-60 years ago.