From what I've read, Bill Pullman and Rick Moranis are set to return and reprise their roles as Lone Star and Dark Helmet. Other cast members include Bill Pullman's son and Josh Gad. While Mel Brooks is also set to return as Yogurt, he won't be involved in the writing or directing of the sequel, it's supposed to have 2 or 3 writers, one of whpm is Josh Gad..
While the involvement of Mel Brooks being limited to playing Yogurt, and maybe being one of the producers, doesn't fill me with a lot of confidence, I'm willing to give this movie a chance. I'm hoping that Brooks will at least have final say over the script and can have it rewritten if he's not happy with any of it.