Yes machines now live on earth, alone.And they kill of most of the animals. But in Cars 2 we see that they are killing each other off because of oil and stuff. My prediction is that the gather all the natural resources and use them all up, and run out of oil and die. the machines didn't know they needed humans to survive. oops.
In Walle, By N Large rules the space ship. Now the machines in Cars are living without humans. And in Walle the machines treat the humans like... Toys. non-stop attention. Luckily the humans put a stop to it, and never use machines again. But because its been so long before humans did anything themselves, they don't know how to survive without machines. And in Walle there are still some animals. The animals repopulate and then the Earth is full of nature.
We see animals create machines that can't think. Sooner or later the animals get smarter than the humans. Then the animals take over.
This is when it gets, confusing. Animals mutated to monsters. Monsters are happily living with machines that can't think. Now they make their energy off of the humans fear feeling in inside out. To do this the doors are time machines to the past where humans live. In the time of toy story and before, humans had a lead feeling of fear, the lead feelings are what power electricity for monsters. The reason happy feelings are stronger is because in Up and toy story 3 is the actual time of Riley, where joy is the leading feeling. Now this gets weirder.
Boo is the witch in Brave. Boo looked and looked for Sully but couldn't. But her life dream was to see him again. So she got something, magic. the doors in monsters inc is similar to the one in Brave when Marida tries to find the potions room. Do you see the Sully carving there? or the pizza planet truck carving?! Or how the potion bowl is like a cell phone?! IT HAS TO BE BOO! And then Boo and Sully live happily ever after.
My Brother JD Showed me the pixar theory and I basically copied him for this.
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