At Gamescom 2015, DICE confirmed that Mirror's Edge: Catalyst is, in fact, a reboot.
During the gameplay demo on IGN's live show, Design Director Erik Oeldahl explained where Catalyst exists in the Mirror's Edge universe. "Mirror’s Edge: Catalyst is a reboot. We basically took the things we really liked about the first game. Faith, first and foremost, the first-person free-running gameplay, and also the aesthetics, which we’ve built on, of course."
Oeldahl continued, "But it’s a reboot. We’re telling Faith’s origin story, so the events of the first game actually don’t really exist. Maybe they will at one time in the future."
Mirror's Edge: Catalyst was one of the highlights of EA's Gamescom 2015 Conference. At E3 2015, EA confirmed that Mirror's Edge: Catalyst will release on February 23, 2015.