I agree with everything you said. Even the part I am about to quote here.
2. Hopefully Devon will drop the belt soon to put over the next guy who TNA can build on. But do so not in a random match but a bit of a feud with some build up.
There is an inherent problem here, though. It would be difficult to write without a heel turn.
I think what they should've done is another one of those "I'm taking the belt hostage" storylines, where Devon turns heel and threatens to leave TNA with the belt once his contract expires, and whoever TNA decides to push, they could've had him take the belt off Devon at Hardcore Justice, and that guy would've gotten over as a hero, as a saviour, with the TNA fans & locker room. What a build that could've been for that lucky person. But I expect people to shit on the idea because it's "copying the WWE".