On the other hand...
The Keyblade is the one toy that is most likely to be missing from the relocated Toy Box. It is the only piece of Intellectual Property that is not owned by the Walt Disney Company. In case Square Enix is not involved in the proposed reboot, much of the storyline still works...
The Villains evoke the worst aspects of the Inside Out Emotions - these new Toy Box enemies could be named "The Negativities" - elemental in nature - flaming lava balls, blue teardrops, green slime, purple spheres that never stop moving, and if Joy is to be part of that mix, trapped golden drops of sunshine to be found & uncovered. The Toy Box could even introduce a new game mechanic - spawned "enemies" that are essentially moving Team Activators that don't drain Health, but rather change your Team designation, vanishing upon contact (with other suggested updates to Team Activators, Team Scoreboards, & the Diffusinator, these could be fun Toy Box games).
Maleficent's Curse could all but succeed in the Toy Box Takeover, with other Villains specializing in certain color-coded negative emotions, such as the Sith with Hate, Maleficent & Green Goblin with Disgust, Ronan with Fear, etc. Boba Fett could hunt down those Heroes more difficult to find & overcome, such as the well-balanced Jedi Masters, or even the glitching Vanellope. Ultron could work against the efforts of Tony Stark & Quorra to retain & transfer the Grid, even when the Negativities turn against the Villains, threatening to destroy the Toy Box. The notion of The Shelves, a new Library of Toy Stories & Toy Games, established by a new space brought into existence by a new Caretaker - the storyline would all fit. They could all play in to a reboot where Community Content has a variety of playlists to help find Toy Box games based on your favorite characters, themes, game genres, character abilities, artists, etc.
For lack of a Keyblade, the perfect Hero to kickstart the Toy Box Reboot is Peter Pan. He was the unrealized Hero of the Origin Space, perhaps the Hero most feared by the Villains' Emotional Takeover Plot. He flies from the combination of pixie dust & Happy Thoughts - he threatens to thwart the Negativies with those Happy Thoughts, restoring the Inside Out Emotions to their balanced selves. For a family-friendly franchise that spans a huge age demographic, he is the boy who never grows up. He is The Chosen of the Toy Box Master Artists. He is the one to lead the recovery of the Lost Toys. With the construction of Library unfinished, he is the best fit to inspire kids to Recapture the Spark. Thinking practically, Peter Pan is also the most likely character most ready to be distributed as a new physical figure, and therefore the best candidate for the reboot disc .