4. He's 006
It can surely only be a matter of time before the new Bond arc starts introducing old characters from former films, and the other double 0 agents would be a welcome return (particularly if they aren't simply presented as cannon fodder). Though Denbigh's officially released biography suggests he's the head of MI6 off-shoot Centre For Intelligence, this Bond franchise has a very specific fetish for presenting characters who you think are one person and then having them revealed to be someone else entirely. Even without the possible revelation that Oberhauser is Blofeld (or someone else is) we're already being lead to believe that everyone is duplicitous and that Bond is an island who has no idea who to trust. So Denbigh might himself be another 00 agent, whose identity is protected because of what happened with Silva. And despite the narrative deception, Denbigh doesn't need to turn out to be a bad guy. Even with the 006 label, he doesn't need to be Trevelyan (at least not yet), as it would be more unexpected at this stage that he's an entirely different familiar name than if he was bad.