At the end of Revolution season 2, nanobots take over Philadelphia and the electricity wire there, what will happen?
The series got cancelled unfortunately, but the writers heard the audience's outcry and announced they would release a comic tying up loose ends in a post on the show's Facebook page, working for "little to no money", in order to pay the fans back.
The four chapters of Revolution: Endgame are available legally, and for free, in the photo albums from the same Facebook page; here's the first chapter.
Basically, (spoilers for the four chapters below)
The war against the Patriots has ended and Miles, Monroe, Rachel, Aaron, Priscilla and Charlie set out to destroy the nanites, which have started to gather people in Bradbury, Idaho (not Philadelphia).
There, they meet a swarm of people who have been turned into nanite-controlled foes, including Neville and Connor. The original plan is to upload a virus which will destroy the nano hive, but that fails and Aaron and Priscilla die.
Rachel states that all she ever did was to protect her family and entrusts Charlie to Miles, who she reveals is Charlie's father. She then surrenders to the nano, becoming part of the hive, but that was only to defeat them "from the inside", by injecting the virus (the code of which she had memorized). As the nanites are disabled, everyone they were infecting die, including Rachel.
Miles, Charlie and Monroe survive, but Connor dying with the nanites got the latter so depressed he goes away, never to be seen again. Miles eventually falls in love with another woman, and has a child with her. It's to that kid Charlie was narrating the whole story, some time after Miles eventually died of age.
It's a good read which actually provides answers to the possibilities opened in the season 2 finale, as well as a non-cliffhanger ending to the general story.