In terms of animated movies, Pixar is now part of Disney (or rather Disney is Pixar), so why the burn with Pixar movie themeing? Dinsey animation has lost any semblance of creativity or touch with their own animation studio, that's why they bought Pixar. Valiant, Chicken Little, and The Wild were average at best, and I won't even comment on the recent traditional animated movies (Atlantis, Treasure Planet, Brother Bear, Home on the Range.)
I certainly don't want WDW to become PixarWorld, but putting in a themed attraction based on a popular movie (or a movie based on a popular themed attraction) has always been done by Disney, and it shouldn't matter whether it comes from the Pixar Division or not.
I can see some concern for purists with scrapping original traditional rides with new themeing or new attractions altogether, and certainly there are some that should never be touched, but there are some that had to go or need re-invention (Mr. Toads, 20,000 leagues, Carousel, etc). The Indy Speedway is old and outdated and needs refurbishment regardless. Right now, it is barely a step above a carnival ride, and with NASCAR's prominence, Indy racing just is not relevant anymore. Either refurbish and re-theme it with NASCAR (and I hate NASCAR), or them it after Cars, I prefer the latter. I agree Test Track probably won't change unless GM gets out (although I think it could be re-tooled into a great Cars-themed ride).