We really don't need a fourth one. In fact, instead of a fourth one, we should get more short form TV specials like Toy Story of Terror and the Toy Story that Time Forgot. Those are far superior than a full on fourth movie. There's plenty of stories left for the characters, just none that could be engaging enough for a fourth full length feature.By now I'm sure everyone knows the lines from the song "We're Doing a Sequel"...
Muppets: "We're doing a sequel, the studio wants more."
"While they wait for Tom Hanks to make Toy Story 4."
Well, consider that threat a self-fulfilling prophecy. Twas announced earlier today that John Lazitor will return to direct TS4, scheduled for wide release in 2017. Make of that what you will.
*Still holds out hope for the Día de los Muertos Pixar film in 2016 and a third Muppets movie in 2017 to complete the Muppet Studio trilogy.
There is a Cars 3, and the only thing to look forward to in that is Lupin III's car from Castle of Cagliostro having a cameo. I accept that. But seriously, we do not need a fourth TS, when the TV specials are adiquate enough to keep the series going. Heck, more Pixar films would benefit from TV specials. I say, give one to Monsters University as a midquel. Do one based on the cut school play sequence.
As for Dia De Los Muertos... there has not been a single update on that one. Strange for a film that was due to be released in 2 short years. I'm sure something may have gone down since Book of Life beat them to the punch. Even then, the cartoonist behind that was trying to get that film off the ground for a decade.