Johnny Depp is a great actor (which is a rare thing for those heart-throb actors in Hollywood). Although Pixar is notorious for not choosing big celebrities to voice the characters, if they had to make an exception for Depp, I’d support them! I think he would do a marvelous job.
Besides, Pixar always makes the right decision for the voice-over actors. They look for the fitting actor who will help the film rather than the famous one that will help the film earn bucks.
sheila
Amen. One of the great things about Pixar is that they do things for the best interest of both their films and their audience. It’s always a disappointment when a production relies on famous actors to drive it, but Pixar is an exception, thankfully.
– Mitch
The thing is, if you use a very well-known actor such as Johnny Depp, there’s always the risk of people associating that character with the actor or any of the actor’s previous characters because their voice is so recognisable. If Johnny were to be in a Pixar film, he’d have to adapt his voice suitingly to the character, but he has been pretty good at that in the past.
I wouldn’t mind if he voiced a character, just as long as his voice suited the character. 
lizardgirl - It seems that Pixar has proven that they can hire well known actors and actresses to play various parts in their films without people being detracted from the character they play in thinking about the voice behind the entity. Heck, some of the first actors Pixar ever called up were (and are) fairly popular, these being Tom Hanks and Tim Allen. And then, of course, there have been other recognizable faces/voices attatched to several of Pixar’s other productions, such as Billy Crystal, Iam Holm, Peter O’Toole, and John Goodman. Generally, though, Pixar tends to select people whom are not that well known in the entertainment industry, which is something I love about the individuals running the studio in that they only…select…people that decently and adequately fit their character, and a good majority of these actors/actresses are people that I, at least, had never even heard of before. I mean, Sarah Vowell? I didn’t know who the heck she was until after I saw The Incredibles. The same goes for Jim Varney, Patton Oswalt*, and Steve Buscemi. Some are quite popular, whilst others have been basically left in the dark until recently, but the important thing is that they all play their parts to a respectable extent.
But yeah, I see what you mean concerning the whole Johnny Depp ordeal. He’s extremely popular now-a-days, so attatching him to a Pixar production may seem a little…unusual or “out there”. But, if he fit the role, I’d say, “Cast him in!” 
*Actually, I had heard of the guy many years ago, but I completely forgot about him until Ratatouille popped up.
– Mitch
Mitch- And the good thing with the well-known actors that they’ve chosen in the past is that every single one of these well-known actors are really respected for their acting. I mean, they’re all well-seasoned professionals which creates the effect that rather than people seeing the cast of a Pixar film and thinking, ‘oh, those actors are everywhere, and sometimes they’re rubbish’, it actually encourages more confidence from the viewer that the film they’re gonna see will be a good one.
I’ll admit, I didn’t know about Steve Buscemi before seeing Monsters, Inc. But, then again, anyone of that sort of age knowing Steve Buscemi would have to have watched some pretty adult films, so maybe that’s a good thing. 
Kinda random…
It’d be alright, I guess.
I agree, he can do just about anything I’m not sure about him voicing a Pixar character, though. I like him a lot, but I just think it would be weird and distracting for me. I liked his voiceover work in Corpse Bride, but I can’t see him doing a Pixar film.