Yes can you imagine Bond having to temporary take over as M in a crisis or have to pretend to be M on a mission? I think that could be fun, especially if he royally screw it up!
I know the real world services are older white guys, but since when was Bond ever true to the realism? 007 needs to keep up with the times, that is why there was a female M to begin with, so if a black man as M is not next, then a black 007 would be the next logical step. Which I would love, but I'd love Fassbender as Bond more.
No other rumors on who Fiennes plays, though? I don't suppose he could be M's son? We know she has children, it would be great to see them. Although I confess this idea of an M backstory or past element does worry me, as that was another iffy aspect to The World Is Not Enough.
Eh. I'm tired of speculating. I want a trailer!