Japan has been succesfully testing railguns for naval use. Not as big or fancy as the projects the US focused on. But limited in scope, and aimed at practical use. They seem to have solved the barrel degrading issues well enough to make the guns viable.

That said. I think it is still too far out to focus on right now.

A lot of the missile defense systems are interceptors, which is basically destruction by impact. Honestly, direct energy weapons would also be better.