OOC: Is this based on a any real life plan? Welles did kick a lot of ideas around, so I wouldn't be surprised if he had wanted to make this (he adapted The Lady from Shanghai from a pulp novel, so a Fleming adaption would be a slight step up.)
Off the top of my head I think a Wellesian Bond series would look and feel a lot like TV's Dangerman--very noir-like, very adult. The kind of things that we only ever saw flashes of in the Broccoli franchise. Most of the gimmicks and tropes would be out, for starters.
There's one problem with the casting, though. Dirk Bogarde hadn't established himself as anything more than a matinee idol at this point, and I'm sure 1955ish Welles no longer has the ability to promote a gifted actor too far above his station (not that Bogarde didn't have real depth--I'm a little amazed to look at his filmography and to find he never did anything noir-like before The Night Porter. Everybody else in the UK film industry had the chance to do some pretty dark thriller roles in the heyday of British films.)
It would be great if an AH-Welles were to cast Patrick McGoohan (in keeping with my Dangerman idea), or Sean Connery, or maybe even Peter Finch, but sadly none of those actors were anywhere on the radar for Hollywood in this era.
Yet there is one young actor who had broken through into Tinseltown from across the pond by the mid fifties--Richard Burton.
Hmmm, launching a wildly successful commercial franchise that just won't die would actually kind of suck for the guy whose ambition was to be the greatest living actor after Olivier.
Or else Orson could do what he did when casting a Mexican hero for Touch of Evil. Get an all-American guy...