In Live+Same day calculations, Once Upon a Time Season 7 averages 2.48 million viewers and a 0.55 rating in the key 18-49 age demographic, and Agents of S.H.I.E.L.D. Season 5 averages 2.29 million viewers and a 0.60 rating in the 18-49 demo.
Now, if Agents of S.H.I.E.L.D. was a big ratings winner for ABC, we likely wouldn’t need to worry about its future, with or without Once Upon a Time.
If Once Upon a Time’s ratings were low enough to warrant cancellation and ABC gets the idea that the sci-fi/fantasy destination didn’t quite materialize, Agents of S.H.I.E.L.D. could potentially be the next show to get the axe.
Unfortunately, the shows have scored very similar numbers throughout the 2017-2018 TV season.