The answer to that question is dependent upon the amount of credibility you give to a tweet made by Paul Thurrott of the Windows Supersite.
My personal answer is I would take that as a fairly safe bet because anyone who has been following Paul Thurrott for any length of time knows that he is very well connected on the Microsoft Campus and has always had a close insider relationship with the company.
Has he missed the target on things in the past? Sure, who hasn’t, but that missed target usually wasn’t because Paul was guessing so I would still take a bet on his prognostications and come out on the plus side of the ledger sheet most every time.
Another tidbit that came out in the series of tweets as he discussed the Windows 8.1 update and its possible release on August 1st was that the product key for downloading Windows 8 will not install/download an ISO of Windows 8.1. The standard installation process for the Windows 8.1 Blue update will be to install Windows 8, or use the built in Reset or Refresh options, and then install the Windows 8.1 update.
That process is probably very familiar to you because it is how service packs are handled in past versions of Windows.
So what do you think – would you be willing to place a bet on Windows Blue shipping on 01 August 2013?