Yes, it will be available as a hub only. However, you *may* need a new receiver kit -- not all the current receiver kits will work with the new SL (off the top of my head i can't recall which ones do and don't work).
I believe it's currently scheduled to be released in mid-November, but the date may change?
I don't have a firm price yet for the hub, but when i do i'll aim to have the best UK/Europe price and be able to offer support on it's use
Ric