If a rumor stemming from "inside sources" is correct, then the PC version of Batman: Arkham Knight will not see a physical release; it will only be available as a digital download on the PC. This digital-only claim is being made by UK retailer, ShopTo, who says that the suppliers informed him that there will not be "physical stock" for Arkham Knight on PC.
Whether or not other regions will see a physical release for the PC version has yet to be revealed and there hasn't been any direct confirmation from the game's publisher. Thus, this news should be treated as uncomfirmed/rumor until there is a comment from W.B.
If you pre-ordered a Collector's Edition for the PC and are wondering what this means for you, well, there's good news and bad news. Likely, the Collector's Edition will be similar to the way Blizzard handles their Special Editions. You will receive the Collector's Edition along with all of the promised goods and there will likely be a download key inside of the box. If one of the reasons that you opted for a physical edition was because of bad internet connection, well, let's hope for a physical release.
Batman: Arkham Knight was recently delayed across all systems, and is now expected to release on June 23rd.
[ShopTo]