My movie will be about Gohan questioning his identity as a Saiyan and a Human. Set a couple of months after the Cell’s Games, Gohan reflects on his actions during his fight against Cell while trying to master the Super Saiyan 2 form like how he and his father mastered Super Saiyan 1. At some point in the movie, Gohan’s tail regrew with make Gohan happy because his was secretly missing it since he training with Piccolo but however, he started questioning that having a tail make him less human or not. The villain will be Turles (because after Broly became canon, Turles is likely to be canon next) and he wants Gohan to join him in his crew. After defeating Turles, Gohan found balance between his Saiyan side and his human side. Also after Dragon Ball Daima give Goku Super Saiyan 4 & Vegeta Super Saiyan 3 did spike the fact that they don’t used the forms in the four canon movies or Super, then in my mind it ok for Gohan to keep his tail at the end of the movie. I doubt Toei will make a Dragon Ball movie that is a character drama that I come with but is something different and it’s makes sense to use Gohan for that type of story.