Having read the interview, I get the sense that Lana might be dropping a hint.
“That’s what he was hired to do, and he’s just so good at it,” Parrilla concurs. “But we’re also really pissed at [Gold], because he set Hook up. It’s classic Gold, classic Rumple to pull an act like this. But we need him. We need him to navigate us through the Underworld. Him being the Dark One is almost kind of a good thing for us, because he is on our team. Even though he’s always pulling these tricks and schemes, he is on our team. Henry’s his grandson. There’s that connection. I don’t think he would do anything to hurt Henry at this point, but I think we’re all pissed at him.”
The way Lana worded it, it made me think that Rumple might be the one to harness his ultra dark powers for good, possibly help Regina beat Hades, and spring most of them out of UW.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy