My first post to the Model X forum!
Elon Musk just said this at the London store-opening event... like, about 5hrs ago.
Check this video at the 24:10 mark. (horrid bandwidth video, but you can hear what he says)
Tesla London Store Opening reception with Elon Musk - YouTube
Perhaps this is for the U.K. market only? The web site still says RWD will be available.