Trion Worlds never really clarified what Defiance 2050 is, which put them in a position to claim they never advertised it as an actual sequel. That said, all of the content is actually from the original game, with updated graphics.
Many players found themselves confused when they started playing Defiance 2050 in the first closed beta test. They started playing the game, became slightly suspicious when seeing the same UI as in the first game when creating a character, and then the opening cinematic rolled out with the exact same characters from five years ago. It was at this point that everyone knew they were playing an updated version of the original Defiance.
Granted, Trion Worlds never specifically said that Defiance 2050 would be an actual sequel, but it's implied when a title is being released anew. The new graphics in the game are definitely better, with better performance. Players fight mutants instead of Hellbugs during the tutorial now and combat is changed to class system, with grenades now being on a cooldown instead of being consumable.
Up to this point, no one actually indicated it will be the same game, with the same story and same missions. I can hardly see any Defiance veterans playing Defiance 2050 since this would be just a replay of the content they completed years ago.
Even with the combat changes, the enemies are still massive bullet sponges even at low levels. Animations and character models are absolutely the same ones from the original game. Even though progression was supposed to be different, it still retains some powers and perks from before.
Improved graphics and skill progression overhaul are an update, not a new game. Then again, an update may not garner as much attention as a supposedly new game, but on the flip side, misleading the community could backfire with extreme consequences.
Trion Worlds have chosen to take a gamble with the Defiance 2050 marketing and it remains to be seen how well or bad it goes for them. The Division is also a looter shooter with bullet sponges but Ubisoft proved that a sizeable update can generate a pile of hype and bring players back as well.