Personally, we can see him in any role, but would mostly wish to see him as a Huntsman. That way, we can potentially see more of him in future volumes where he'll stand less chance of being killed off.
This is another franchise where we can see him in just about any position, however, few sound better than a Grey Jedi as a chance for him to use his roguish charm.
James said he'd return to Torchwood in second if they ever had a reunion, but this is only a step-up from that opportunity, and promises him greater chances from there.
We'd see James as potentially a Federation Officer, or a renegade ex-Star Fleet official as either an effective aid or a fitting adversary to the likes of Captain Kirk. Either one would be good, as you can never have too many great villains in the enterprise's opposition, and they no doubt need a new comrade to aide them given the death of Anton Ye
In this show, we reckon he'd be able to play either your typical gangster archetype, or even a potential opponent for Saul in the courtroom. As he's no slouch in the intelligence department.