While I've really enjoyed the recurring bit, I'm skeptical it can support a 30 minute show, let alone a series. That said, I'm sure they'll be moments of brilliance that I'll gladly watch on YouTube (just as I do will Fallon). Also, I don't think it's difficult to rank the participants. Stone for the win, JGL a close second.
It's the only good part of the show, except for the occasional children instruments bit, so why not. Just cancel the Fallon show and replace it with this.