I'd love Hurt to be The Other but I assume he's a Doctor between 8 and 9. The way he was described as breaking the promise, I'd assume he has to be after the original Doctor and the only place he'd fit in the timeline would be between McGann and Eccleston.
! So are you saying that this terrible thing he did, this breaking of the promise, was related to the Time-War? I had always assumed that McGann's regeneration into Eccleston took place during, or at the climax of the war.
Intriguing to think that there might've been another version between them. I still think that he could be the original version, pre-Hartnell, but probably will be proven wrong.
Either way, it's great to see JH in this show.