Tonight's Once Upon a Time isn't just notable because its the finale, but also because the first official promo for the much-hyped Marvel's Agents of S.H.I.E.L.D.will be airing at some point during the broadcast. You can check out the teaser here. Could Once Upon a Time get a bump as a result? Or will those interested just wait until the promo hits the Internet? Make your ratings predictions below and tell us why in the comments!