Such predictions are nonsense. Evolutionary changes act (over a considerable period of time) on characteristics which favour survival to breed. Since human beings are capable of getting round problems by ingenuity (rubber flippers to aid swimming for example) and look after the genetically disabled rather than letting them die, there will be nothing for evolution to act on. It is more likely that we will see strategic breeding/DNA manipulation.
After tonight's walk to the ground, it can't come soon enough!