Luxy's Space Adventure was to be set aboard the intergalactic cruise ship Luxatainia, where the Vault Hunters were to have a well-deserved getaway, until space pirates boarded the ship, and the other passengers began to mutate into plant-like zombies.

A lot of this canceled Pre-Sequel DLC content was re-purposed in to a Borderlands 2 DLC named "Litith and the Fight For Sanctuary" 

This DLC could be made and then be put in to the Handsome Collection similarly to the last Borderlands 2 DLC. 

Please Gearbox, a lot of us really did enjoy the Pre-Sequel and want to see the game just get a little more content.