Then that 007 would have been a different person. A guy called John Dudebro for all it matters. 007 is the codename. James Bond is his birth given name. There's been numerous 006's before, but only one was Alec Trevelyan. Once presumed dead, his 006 status was passed onto a different operative.
I don't know why people act as if Skyfall has ruined the "codename" theory. The "James bond is a codename" theory is a load of utter shit. Reasons:
1. Bond's heritage and past are described in Ian Fleming's OHMSS novel, which was then used in the 1969 film, such as the use of the Bond family motto - "the world is not enough" and a firm focus on Bond's Scottish upbringing.
2. Tracy Bond's death in OHMSS is subsequently referenced by Roger Moore's Bond, Timothy Dalton AND Pierce Brosnan.
3. Bonds' parents were killed in a mountain accident. This is brought up in the OHMSS novel, Goldeneye, and Skyfall.
4. Bond's Scottish upbringing is brought up again in TWINE and Skyfall.
5. Different Bonds have reminisced, talked about or directly referenced past missions in the series (eg. Lazenby with items from the Connery films in OHMSS, the DB5 in numerous films).
6. Bond's relationship with Felix leiter - David Hedison plays him in Live and Let Die and Licence to Kill, beside two different Bond actors. It is VERY clear that the Bond character is the exact same person in both. If each Bond was a different person but using a codename, none of the Leiter interactions would make sense.
Basically, every single last bit of evidence proves that James Bond is one person, and always has been. The character is on a floating timeline, and can effectively live indefinitely in this series of films.
That's it really.