The first hints of a PlanetSide sequel happened back in 2009 when developers sent out an email to all PlanetSide players asking for help in designing the next iteration of the game. Players were provided a survey and the game was confirmed as PlanetSide Next, before eventually being renamed to PlanetSide 2.
Right on target!
PlanetSide 1 players were delighted to find a BattleFrame Robotics tucked away in hangar in Indar, but soon disappeared after a performance update was administered. The easter egg had to go in favor of optimizing the game and besides, BFRs are OP.
PlanetSide Next was never intended to be a sequel to the original -- the developers considered it a polishing effort, but because the game engine was so limited in what they wanted to do, they decided to completely re-imagine the game with both new art and a new engine, resulting in PlanetSide 2.