IIRC this has already happened with Tay-Sachs, although not by editing, just by testing (either before marriage, or of embryos). I think the disease is now more common among non-Ashkenazim, who are unlikely to be tested.

Seems like a useful test case to think about, and read about, rather than relying only on imagination.

That's not something that you can decide for other people. If some people like their sickle-cell gene no one can force them to remove it, and similarly if they don't like it no one should be able to force them to keep it.