Even if he said that, it just isn't possible... The planning, block building and and simulation alone takes about a year, tape-out of a new chip is around 8 months and then it takes periods of 3-6 months between production candidates and mass production. And then you'd need at least 6 months for packaging and assembly.
The X360 was developed in record time, had its IP suppliers (IBM+ATi) defined in August 2002 and a console released in November 2005... and even that came at a great cost to Microsoft because they didn't do the proper QA protocols leading to the Red Ring of Death.
And Microsoft believed the PS4 wouldn't exist? I mean really?!
Without sounding like a dick, were you out of school (adult etc) during the 360 generation?
A lot of stuff happened during that time that many people don't remember or realise.
The Durango leaks (a document supposedly detailing the specs of the X1) that were slammed by everyone - and most called fake because of how bad the console sounded, turned out to be real. Major Nelson and co admitted the quick turn around in the X1.
The media, Microsoft and foolish gamers, were told/led to believe that Sony was bankrupt and PS4 wouldn't exist. They changed it to it would exist but it would be over priced and underpowered...exactly what the X1 was.
This led MS to a false sense of security and dragged the generation out. They released a revamped Xbox 360 in 2010, rather than a new console that would have sunk Sony.
So, much in the same vain, MS could and will release many SKUs, maybe some with very little notice like the Xbox 360 slim slim. (Not a typo).
I made a thread under another name, detailing how Microsoft release multiple SKUs in their generations and not one has been released, let alone launched, 3 years in. In the thread (iirc) I asked the question if MS would drop out of the hardware race or, more likely, make a Series SX and discontinued to previous SKUs.
Edit: Xbox 360 was rushed and corners cut for two main reasons; 1) Nvidia had them by the balls with the OG Xbox and were charging an arm and a leg to continue making the old tech, and 2) Peter Moore signed, what he calls "the biggest cheque of his career". It was $1 billion to increase the ram from 256 to 512mb unified. He signed it because cliffy B showed him a side by side comparison of gears of war running on both configurations.
