This is developing story.  I wonder if all these protests demanding his resignation was responsible. WGN is live talking about it now.
https://wgntv.com/2018/09/04/rahm-emanuel-will-not-seek-re-election/
https://wgntv.com/on-air/live-streaming/

My guess is he knows the pension system will crash in the next 5 years. He doesn't want to deal with that heaping pile of shit.

During his tenure as "Chief of Staff" during the first Obama term, Rahm Emmanuel was labeled the "Ballerina" for his ability to "dance" around sensitive questions at White House press conferences. I imagine he can't "dance " his way around the Laquan McDonald controversy. To paraphrase an old tome, "It was never a question of "if", only a matter of "when". I would think that Rahm's refusal to seek re-election would open the door for Democrat candidates that don't carry the backing of the "Old Guard" that pretty much insured Richie Daley's election victory. Time will tell.
Regards,
Gary

No worries, they'll elect some equally shitty mayor to replace him.

I guarantee whoever they elect will be far worse.  He was probably the only one who might've been able to start to turn around the finances of the city, if given a 3rd term.  He'd already done more to fix CPS and starting to fix pensions than any previous mayor.  He was pro-business and it translated well with the business community.  I'm only judging from a fiscal standpoint - not even going to touch is 2A stance, since it's a given that no Chicago mayor will be pro-2A.