The midfielder quit Sunderland for Newcastle last summer.
Colback told the Evening Chronicle: "It definitely still feels like a club where, if everything went right, it could be incredible. Everything's here for that to happen - there are great foundations for the club to go wherever it wants to go.
"You've got to be sensible with that because there are clubs that have overstretched in the past and that are in a mess now. There's a certain level that's realistic to get to, although that's out of my hands. It's a club with potential, and it deserves to be higher up the league than it has been. Hopefully, we can have a right good go next season."