Swirly D is just a vulgar prankster and a bully. He should be among the harder of bosses, but in my opinion he should be no means be the last foe we face in Juice Galaxy. I admit this is partially selfish; Both in gameplay and lore/world-building wise, it'd really disappoint me if that equivalent of a pothead middle school dropout was decided to be the toughest non-scaled foe the Juice Galaxy has to offer.
Granted I can't speak for Fishlicka, but with how creatively this game has been growing and picking up steam, I can't help but hope that we are *at least* twelve more bosses away from even beginning to think about a/the "final" boss. Juice Galaxy's oddity gives a nearly infinite possibilities for combat and trial.