Rob Zombie was joined on stage by original guitarist Mike Riggs for his Aftershock Festival set, telling the crowd Riggs had returned "after a 20-year absence." Zombie didn't say anything else about if Riggs was a permanent member of the band or where John 5 is (or if he's even in the band anymore), though I'm sure there will be a statement incoming if Zombie's band has undergone a change of that magnitude.
In the meantime, check out fan-filmed footage below courtesy of Blabbermouth. Riggs was a part of the original Rob Zombie band that recorded both Hellbilly Deluxe and The Sinister Urge. Riggs left in 2003 and was replaced by John 5 in 2005.