Which sounds like a reasonable assumption at any rate.
We already know that Microsoft has begun work on a new Xbox- Phil Spencer confirmed it in as many words on the E3 stage during Microsoft’s presser on Sunday. But even if he hadn’t, this would be basic common sense. Companies usually begin to work on successor console hardware as soon as their current hardware is out. Hardware research and development is a long process, full of trial and error, and evolving and mutating scopes- you need years to work on it, it is not something that can be done overnight.
Which is why the announcement at E3, which also indicates a release closer than many may have expected, wasn’t that much of a surprise. And while many will speculate on when the game console may actually com out, according to Thurrott, known for having well placed sources within Microsoft, the system is due out in 2020. Which means two years from now, and three yeas from the launch of the Xbox One X (which itself was released four years from the launch of the original Xbox One).
I suppose that sounds like a reasonable time frame- it would mean the console launches seven years after the Xbox One launched, making this generation about as long as the last one was. I do wonder if Xbox One X fans might not feel jilted by something like that, though- they were promised the most powerful console ever, and they only got to keep it for three years.