Any system that comes along and can prove itself to be superior to an existing program should of course supersede it. Whether that is needed is another issue entirely. I do think that as it stands, NATO hasn't caused any trouble (that I know of) and could be comfortably left alone.
No, NATO is not a relic, because NATO is still well-respected around the world among the member countries. Whenever there is a NATO summit, it is widely followed by journalists, and even talked about by Americans. NATO is a trend-setter, and it remains a leader in peaceful negotiations between countries.