It's more likely to be that if you subscribe you get the PDF but if you preorder you won't.
It's not yet been revealed exactly how the subscription options will pan out (whether there will be one, two or more subscriptions and how the different product lines will be split between them). The latest I heard (on Friday I think) was Vic Wertz who implied they'll be ready in plenty of time for August (but probably not imminently).
My impression was that there's lots of tweaks to the forum architecture behind the scenes and that they're testing how everything interacts before going live....But I confess I'm reading rather a lot into the words he actually used. :p