Microsoft has stopped selling new Xbox One consoles in the US and UK. Technically, it's listed as "sold out" on the Microsoft Store and doesn't even show up in searches for Xbox systems. It seems the original version of the console that launched in November 2013 has finally been retired; All hail the slimmer S and souped-up X versions.
Microsoft confirmed to Console Deals that they have retired the console. If you really wanted to, you can still buy a refurbished original Xbox One for $200 on the Microsoft Store, which is $50-$80 cheaper than you can find its replacement, the Xbox One S. Or you can join the horde of psyched users who already preordered a big-but-undisclosed amount of Xbox One X's for $500 and wait for it to launch on November 9th. Either option will arguably look better on your shelf than the original console's odd VCR facade.