Surely Amazon with a minimum of forewarning won't have any problem with this.

It's the same for bookstore chains. Tor would send out a nice promotional flyer warning them of the new release date, and stores will order the book. And the distributors will deliver them.

All these people are in the business of distributing and selling books. That's hardly the first time there's barely time between the author delivering a manuscript, the release date being announced and the book hitting the shelves. In fact, it's become more common in recent years, apparently.

If Tor has decided to move up the release, all the logistics will be taken care of (that could be a reason they're not already announcing the release date, they might be dealing with the last details to choose one week over another because of distribution issues and all - it's a peak season for book releases after all).