Magic Kingdom will be without a night parade for another three or four years. They'll announce something at the 2019 D23 Expo, and then debut it in late 2020 or early '21, whenever WDW's 50th celebration for 2021 kicks off.
I'm sure there will be Pixar floats in whatever WDW night parade they get. There are two major Pixar attractions already in Magic Kingdom Park; Buzz Lightyear Astro Blasters and Monsters Inc. Laugh Floor.
Right now WDW has a very, very weak parade lineup. They have exactly one (1) daily parade across all four parks; Festival of Fantasy at Magic Kingdom.
Anaheim has three (3) daily parades on offer currently; Pixar Play Parade, Mickey's Soundsational, and MSEP. Plus two nightly Fantasmic!, two nightly World of Color, and Remember fireworks. Disneyland Resort is an embarassment of riches compared to WDW right now, but we're all supposed to wait for the 50th in 2021 for it to get better.