I have no problem at all with Idris Alba being Bond. If M can be a woman then Bond can be black.
George Clooney being Bond? No effin' way. Why not Brad Pitt, or Johnny Depp, or Robert Downey while we're at it? At least we know they can do fake British accents. Commonwealth country actors only thanks (have to say that because Lazenby was an Aussie). I love George Clooney as an actor, but as Bond, no way.
It's not comparable with Blade or Superman, because those are graphic novel / comic book characters, so their images are set in stone. A blonde Superman would be just as anathema as a Superman of another race. Bond has no essential visual image. Then again, one day the world might be ready for a Japanese Superman. Superman is, after all an alien, which means he could probably use his superpowers to change his visage if he wanted to.
The one thing against Idris Alba, is the casual racism which demands that Bond always be white, because of reasons. That would potentially diminish the market for an Alba movie because of the "Bond must be white" crowd.
If the world was truly colourblind then then Bond's race would be a non-issue, as long as he's a Brit.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
