The Xbox One will receive support for game storage via external hardware in a forthcoming update, Microsoft's Major Nelson confirmed in a Reddit comment this week.
"Lots of good work going on to make the console even better - some you'll see soon, some will show up later," he said, later adding, "External game storage is coming soon."
Nelson was unable to confirm the maximum storage size the Xbox One will support, and a timeframe for the update was not announced. The Xbox 360 enabled external storage in a 2010 update, later expanding its support for devices up to 32GB in size.