Even if it doesn't lead to a medical treatment, the impact of CRISPR on everyday biomedical research has already been enormous - it's probably the biggest advance in molecular biology lab techniques in the past decade. Getting it to work in humans is of course a huge project, and we can expect many failures along the way, but genetic modification is vastly easier than it was 10 years ago, when we barely had any idea how to make these kinds of changes. Every improvement to the technology makes it that much more likely that we'll see a human application in the near future.