By this logic, you can take it a step further.
Cook knows that the first version of Maps will be weak, so he puts Forstall on it. Cook knows Forstall is headstrong and wont admit a mistake.
Maps comes out, gets bad press for its problems, Cook and fam issue an apology without Forstall, who states there was no problem. Weeks later, a major executive shift to oust Forstall and put Cue in charge of all online services.
We might see these power shifts of unlikely or ridiculous, but I bet a lot of this is true cause how else could you get rid of someone so high up without good cause? Cook deliberately putting Forstall on a known to fail project simply to out him from the company because everyone doesn't like him makes sense.
I mean, at the least, the timing is very plausible. if they had waited 6 months to announce Forstall's departure, then I would say the above is doubtful.