Not sure. Could be that Marvel had the Mysterio rights, while Sony had the actor's likeness rights. Seeing that it was a Sony production of a Marvel property. And when they had a falling out they couldn't include the headsculpt, because Sony wouldn't let them.
Mind you, this is my speculation. Nothing is confirmed or anything.
Ya I guess it?s a wait and see but really hope that we get a headsculpt. Jake gyllenhaal is awesome as mysterio.