I'm no gossip and I can like from now til the end of my days without hearing the tiniest tidbit on Hollywood infighting, but you have to wonder what could have happened to make Edgar Wright abandon a project he seemed born to create, not to mention on he has been working on in one way or another for a good long time. We could assume that the studio has a strangle hold on all projects moving forward to assure their success and cohesion in the Marvel Cinematic Universe, but hell, if James Gunn could introduce the Aholes of the Universe and come out smiling, what obstacle could be so insurmountable as to make Wright up and leave? We may never know the answer, but the new director will certainly have massively geeky shoes to fill.
For my part, I know Edgar Wright is good people and I will sorely miss his take on that little corner of the Marvel Universe. Best of luck, Edgar!