The toys and Life Day special were meant to get fans excited about Boba Fett, but that all changed when George Lucas realized during The Empire Strikes Back that he wasn’t feeling doing several more movies.
This news came from Craig Miller, who noted to Inverse that the proof is in the marketing of Boba Fett prior to the movie’s release.
Boba Fett would remain, but he went out like a chump.
Instead, he’d close it out after the next one, keep Vader on as the big bad and condense the entire Palpatine trilogy he planned to one movie.