WALL-E was an amazing film. Christopher Nolan is an amazing director. So let's play around for a second and hypothesize how utterly brilliant it would be if Nolan had gotten the chance to direct WALL-E? Though I am not sure that movie could get much better, you do know a couple things right off the bat if you know the director's work. It would be a dark and gritty film, the score would be so powerful you would feel like you couldn't breathe while watching it, and it would have an ending that left you in awe (or a tad bit confused).
So really, Christopher Nolan should stick to what he does best (Interstellar looks unreal), as should Pixar. This still looks like it would be an amazing film, though, and is a fun way to spend two minutes.