If you are looking to integrate the RealSense cameras into a product, then the USB cameras can be used for prototyping. For the final product though, I would recommend using the caseless 'Depth Module' circuit board version of the cameras. You can use these in a commercial product, whereas the cased USB cameras are not recommended by Intel for this purpose because they have a limited 90 day warranty.
If you want to source the Depth Module boards in limited quantities then you could order them from a company in your country that is an Intel Authorized Distributor. If you want to source the parts in large quantities (e.g 50,000 +) then you can open a sales inquiry ticket with Intel.
You can learn more about the module boards for the latest 400 Series cameras by going to this page and clicking on the 'Depth Module Specs' button about two-thirds of the way down the page.
If you wish to put a RealSense camera inside a product that you are going to sell then I would still strongly recommend using the caseless Module Kit boards. If you supplied a product with the cased USB camera then it is unclear how the warranty could be claimed on, unless the customer returned the camera to you (the original purchaser of the component). And then it is unclear whether you would be covered by the warranty, as you were not the end-user of the camera and had passed it on to another person (the purchaser of your product).
If you just wanted to use the USB cased version of the camera for prototyping then I see no problems with claiming on the warranty if the camera develops problems during the warranty period.