Sure CaptainSwan is no more, but the Hook fan base is fairly extensive and Colin has a very big fanbase.
The CS and Hook fanbase are the same thing and many refuse to watch after Sunday.
And yet there was a petition going around asking ABC for a Hook centric prequel staring Colin. Now maybe that’s a small portion of that selected fanbase but the idea that they’re totally going to drop the show doesn’t quite scan because they obviously like the idea of Colin/Hook, Emma or no. Especially if Hook’s story has something to do with saving Emma. Reading through comments on SpoilerTV and Twitter, yes many are saying they are done, but many others are saying they’ll give it a go if A and E does right by the ship by having the story be about the ship (ie: Emma’s in trouble, missing, pregnant and under a sleeping curse).