NECA (Beetlejuice, Batman) and Hot Toys (Batman and Batman Returns) clearly sport Keaton's mug. I don't see why Sideshow wouldn't be able to. Keaton has unique defining facial features like his brows, eyes and lips. I'm sure Sideshow's Beetlejuice will sport them. Why pursue him if they couldn't?
After seeing their Pilot Luke, my prediction is, we'll see an amazing prototype with a fantastic likeness, great tailored clothing and fun accessories/gags that people will drool over. Then . . . . then the prototype won't even live up to it.