Xbox One by iFixit revealed that the console uses a variety of common off-the-shelf hardware components, including a standard-sized hard drive for storage.
iFixit notes that the Xbox One is equipped with a standard SATA II, 2.5-inch, 500GB Samsung Spinpoint ST500LM012 hard drive with an 8MB cache. Contrasting the proprietary hard drive casings used by the Xbox 360 and the recent Xbox 360 "slim" model, off-the-shelf replacements for the Xbox One's drive are readily available. Replacing the unit could prove difficult, however, as accessing the Xbox One's hard drive involves prying open the console and removing its Wi-Fi component and system speaker assembly.
iFixit was unable to determine whether the Xbox One will recognize an unformatted replacement drive, however, so it's worth waiting for Microsoft's promised USB storage support before busting out the crowbar on your new hardware. iFixit's ongoing teardown additionally revealed that the Xbox One uses standard Torx screws, SATA connectors, and other easily-replaced components, possibly aiding future repairs and maintenance.