Post End Game Bosses, Items, Storage, etc...

I do think that the game in its current state could be considered complete, but a lot of us like to keep playing passed completion or even make a new world with our old character.
More optional bosses, difficulty modifiers for earlier bosses, and even customizability for bosses to gain rewards for end game gear/new things.
Maybe make "Boss Food" that requires rarer fish/ingredients that you can drop next to a summoned boss. It will eat the food and gain some sort of buff along with increased drops.

End game gear that has unique traits. The end game drill has chain lightning. The end game pickaxe drops additional ores from walls. These are special traits and more special traits would be nice.

End game terminal based storage/crafting.
Placable terminal that grants access to all storages within range. Could even link the crafting stations to it with upgrades. A modular terminal of sorts.

A pet build that works passed mid game would be nice, but I'm out of text space for this post.