The "US national" status is a legacy of the Insular Cases, and all the other cases formerly in this bucket have either gained independence (Philippines) or become full US citizens (Guam, Puerto Rico, Virgin Islands).
So in the hypothetical case that American Samoa is returned to Samoa, the logical options are to either make all American Samoans citizens of Samoa, or to give them the option to choose between Samoan and American citizenship. In either case the weird "national" status will cease to exist.
So in the hypothetical case that American Samoa is returned to Samoa, the logical options are to either make all American Samoans citizens of Samoa, or to give them the option to choose between Samoan and American citizenship. In either case the weird "national" status will cease to exist.