Here’s a conspiracy theory that has been floating around. Some have suggested that Obama is timing his executive amnesty announcement to coincide as nearly as possible with the Ferguson, MO grand jury announcement, which is almost certain to be no indictment, and thus decrease the impact of both with a constituency that largely overlaps (the pro-Wilson and anti-amnesty crowds). (Both have been widely predicted to happen Friday.) Assuming there is rioting as a result of the grand jury decision, which is possible but not a foregone conclusion*, an amnesty announcement would take focus away from that and divide people’s anger.
*Everyone is predicting riots, and they may happen, but everyone predicted riots following the George Zimmerman verdict, and they largely did not happen. I think the prediction of riots and preparation for them makes them less likely.