I'm not so sure 'Northern Soul' isn't a dance genre rather than a genre of music. You see in my befuddled head the people in northern England who danced to obscure sixties soul music created a dance movement they didn't create music. They discovered music they enjoyed dancing a style of dance to. Tracks so co-opted became Northern Soul. So, if it fits as a Northern Soul dance, its Northern Soul music.
Talk of 'modern' isn't even relevant in my mind (I'm a dancer). Watch a video of 'Northern Soul' being danced, with the sound muted and you'll see what I mean.