The major immediate impact will be the treatment of many genetic disorders like cystic fibrosis and inherited cancer risks in those currently existing. For example, control genetic expression to turn off genes like BRAC-1 and others that raise the risk of cancer.
Next will be the use of genetic engineering to cure disorders. It will be much more acceptable to use genetic engineering to remove tendencies like diabetes, Alzheimer's, heart disease risks and so forth than improvements.
It is certainly possible that genetic engineering will be used to try to improve the species. The challenge is that it creates people who by definition would be at the top of a merit based society, thus able to dominate it, since their parents had the money and connections to get their kids genetically enhanced.
It won't alter the species on a large scale for generations, because it isn't yet reliable and proven. Would you take a chance to spend tens of thousands to improve a potential child, when you don't know if the traits will take or the impact on their lives once grown? Or that the traits added for certain benefits won't be dangerous in excess?
There is the possibility that human subpopulations might be created to suit some purpose, but in a world approaching 8 billion people, it is cheaper and easier in such a world to alter existing humans that create them, raise them and hope you get the intended result like a super-soldier.