Microsoft's Major Nelson has been speaking on the Xbox One reddit and has stated that external storage solutions will be coming soon to the next generation console.
Just look at that grin!
Hyrb was repling to a comment from a Reddit user asking if there was any update on the ability to use external HDD's on the console.
"Lot's of good work going on to make the console even better - some you'll see soon, some will show up later. But: it is all good stuff :) - External game storage is coming soon....I need to check on media support."