I was pretty hyped for Toy Story 3 when it was first announced.
Not sure exactly how I feel about Toy Story 4.
Its story sounds interesting, but the third one ended perfectly. I'm not a big fan of Hollywood's interests of rebooting/sequeling everything, but Pixar does a good job with their movies. Heck, not even Pixar escaped the dreaded sequel bug however.
Although I must say that I'm kinda excited for Cars 3.
***edit: I saw Cars 3 not too long ago, and it was really great! I'd say it's the true "Cars 2" sequel! Don't get me wrong, I liked Cars 2, but Cars 3 was waaay better! I recommend giving it a watch!