WWE announced today that John Cena has been added as the fifth member of Team SmackDown at Survivor Series.
The match will now be: Team Raw (Kurt Angle, Braun Strowman, Finn Bálor, Jason Jordan, Samoa Joe) vs. Team SmackDown (Shane McMahon, Bobby Roode, John Cena, Randy Orton, Shinsuke Nakamura)
Further proving #SDLive is the superior brand, I'm happy to announce @JohnCena will be the 5th member of Team Smackdown at #SurvivorSeries.
— Shane McMahon (@shanemcmahon) November 8, 2017
It had been reported that WWE was originally planning on using Cena as a special guest referee for the Brock Lesnar vs. Jinder Mahal match, but that match has now been changed to Brock Lesnar vs. AJ Styles after Styles won the title from Mahal last night on SmackDown. AJ Styles was originally planned to be the fifth member of Team SmackDown, so Cena will be taking that role.
The decision to change things around and remove Jinder Mahal from his match (and the card) was made last week by Vince McMahon, according to PWInsider.