This page was an adaptation of Shroom Tube's video on the same topic. Here's the link: 
Disney Infinity was a sandbox game made by Disney and Avalanche Software in 2013. The game had you collecting figures in the real world to use in the game similar to Skylanders and Lego Dimensions who pioneered this style of game. Only this time it was made with the Disney, Pixar, Marvel, and Star Wars brands.
Here's where the adaptation begins.
The game's internal development, a well as the studio, were closed in May 2016 due to low sales. Because of this, Avalanche Software no longer exists and over 300 jobs were lost. Disney then decided to license out their brands to other companies, instead of making them themselves. In 2016 Disney didn't release another installment, to increase the life of Disney infinity 3.0, thus making it the largest in the series. This was said in their Disney infinity next presentation, and they had big plans.
Aside from the Finding Dory and Alice Through the looking Glass content that was released, there would've been characters from the following films: Rogue One, a Star Wars Story, Being worked on by Ninja Theory, and Moana, being worked on by Studio Gobo. Believe it or not, 12-inch (30.48 cm) figures were planned as well. Some of their most popular characters would be made in this fashion. Those characters included Buzz Lightyear, Elsa, Jack Skellington, Hulk, Hulkbuster, and Darth Vader. According to an anonymous source working on the game said this: "The figures, set for this fall, at $45 each, (for those in Britain or somewhere else it's about 34.93 sterling pounds) would've featured more detail, lit up, and acted differently in game.". They also said "They looked f*ing cool.". These weren't the only cancelled figures though.
At D23 2015 the toy box artists' choice character was revealed to be Peter Pan, a classic Disney character, that would be released 1 year from the presentation. As well as being labeled "Toy Box Artists' Choice". Sadly, Peter Pan (Fun fact I'd actually like to see him) was cancelled once the studio shut down.
In their Disney Infinity Next presentation, they stated that at least 1 more playset would be released for each of the core brands, Disney, Pixar, Marvel, and Star Wars. Finding Dory was Pixar's. Moana would've been Disney's. and Rogue One would've been Star Wars'. But the final Marvel playset was never stated in the presentation. Sure we have Marvel battlegrounds, but that was in the works since 3.0's initial announcement. According to the MCU (Marvel Comic Universe) the next movie to release after Captain America: Civil War was Doctor Strange. The playset could've been based on the at the time upcoming movie.
Disney Infinity 4.0 was a cancelled sandbox-adventure game developed by Disney Interactive and the now defunct Avalanche Software, and would've been the sequel to Disney Infinity 3.0, and the 2017 entry in the series. Even though this would've been the 4th installment in the series, the numbering would've been dropped. Just labeling it "Disney Infinity", since it's not a game anymore. It's a platform, just releasing a new installment every year. The new installment would just be an installment. According to an anonymous source working on the game, the game would've included content from Cars 3, Star Wars Episode VII (or 8 for those who don't understand roman numerals), Pirates of the Caribbean: Dead Men Tell No Tales, Thor Ragnarok, Guardians of the Galaxy Vol. 2, and the Pixar film Coco. It also seems that Hasbro was asked to assist in the figure design.
Another weird thing was that there was a Toy Box story mode planned for Disney infinity 4.0. All characters could join. No restrictions, no limits, in a campaign style. The campaign was almost like Toy Box Takeover in a sense, but much better. The game was cancelled when Disney shut down Avalanche Software and Disney interactive in May 2016.
As of writing this, the servers are still online.
Here's Shroom Tube's video where I found this information. I was just mirroring the information.