Several things here...
Why would Billboard showcase an old track, out of the blue ?
Also, Kleinenberg may be a dance legend for people who follow the DJ scene, but Billboard isn't an edgy media, it's more mainstream than anything else. Talking about a shape shifting dance legend very few know about wouldn't give them much credibility at the end of the day.
If it has nothing to do with Madonna, either she or her staff AND Billboard should deny it. Yet again, nothing has been clearly stated about this yet.
As for her still being in the studio : in this day and age, why would that prevent her from releasing a track ? It's not as if she had to rely on CDs to be in stores to sell her single.