Bond's CIA buddy has seldom been played by an actor who fit Fleming's description. A black actor played him in Never Say Never Again as well as Casino Royale. I don't see why Idris Elba can't star as a new character in his own series. During the height of Bondmania in the 60's there lots of imitators, like Our Man Flint, Matt Helm, The Man From U.N.C.L.E., Harry Palmer, et al. They better hurry, though. Sean Connery was in his early 30's when he started as Bond. Elba at 45 will be a bit long in the tooth after a few films. I think Craig is looking a bit too old.
I really do think Bond and the whole British spy thing is out-dated now. Bond was created at the height of the cold war, when it was the West against the Communists. Now the U.K. is so overgrown with potential terrorists I'm not sure whose side they are even on these days. I would like to see a Bond film set in the 50's and based on one of Fleming's actual plots.
Roger Moore was 45 when he played in his first Bond movie Live and let Die.
You are right Elba is already too old. Bond is not supposed to be some old guy. He is supposed to be young. I hated watching a near 60 year old Roger Moore try to look suave with a bunch of twenty something girls. He just looked old. Bond should be 30 so they can knock out three to four movies before he looks like an old lecher.