I believe it is just considered a separate story. Technically it is a prequel since it was when he first became Bond, but for the most part it is just a story to tell. I'm assuming the next one will be considered between this one and what has been made in the past, but there may not be much mention of what just happened either.
Its not like Batman Begins either. Batman Begins is a true reboot. The intro to Joker has already been different and the movie is definitely not considered a prequel by its makers. Bond is always referred to as Bond 21, showing that the creaters see it as the same series.
Greg Oden: The future of the Blazers. The future of the NBA.
Its a prequel but only so much as Bond could have a prequel. Bond doesn't really happen to have any real continuity to follow. Although Casino Royal is supposed to be the "first" Bond and thats where the confusion comes in as the other bonds could be randomly shown in a random order and still make sense as there is no real timeframe. Thats why is confusing as it is the first one to say "this is the start of the Bonds" but the rest of them have no actual order in terms of continuity.
As crazy as it sounds the Bond we saw the last of in Die another day, was still meant to be the same person who was in from Dr No.
Bond reminisses on past adventures as Sean Connery, when he threatens to resign as Geroge Lazenby.
GL gets married, and when she dies, SC comes back for one last (official) time, to get revenge.
Roger Moore visits the grave of his wife in one of the later films, so we know he is still meant to be the same person too, plus at that point, all three actors so far had been roughly the same age, in fact Moore is a year older than Connery.
The actor playing Bond then got younger when Timothy Dalton took over, but it was still meant to be the same Bond, who still mourned for his wife, and they even tied him in with the first person to ever return as Felix Lightner for two films in Licence to kill.
Brosnan again still mentions the dead wife, again still locking him down as the same character, if you want to justify how young he looks, then you have to say, the old films still took place, but not nessisarily in the years we are used to them taking place in.
Kind of like how the year Homer and Marge met keeps coming forwards in the Simpsons as they are locked into meeting half a year longer than Bart is old, and since Bart never ages...
Daniel Craig is the first Bond actor who comes with no back story, no continunity, I know the fact that Judi Dench is still M is confusing, but she was locked into a contract.
And since they have started again, this means all the books can be made again, if they want to go down that route.