Sure, hardware updates are new, but even the PS4 as a much healthier platform than the XB1 could increase its sales by only ~3m in the year after the PS4 Pro launch. The XB1X, which retails for $100 more than the PS4 Pro, would have to lead to ~5m of additional sales year over year. I mean, it can't be ruled that the XB1 finally manages 10m in a calendar year, but 13m is a different ballpark.
You cant compare the XB1 to Sony this generation. PS4 is the market leader and was selling like hotcakes regardless of which consoles. The announcement of Xbox one X has been hurting XB1 sales since 2016, hence why XB1 did worst in 2016 compare to 2015, 2016 the system should of been selling at a lower price point.
Xbox in 2017 sold roughly 8.5 million in a year of uncertainty and waiting for Xbox one X.
I think it's safe to say that XB1 should reach 10m sales this year. I expect Q1 2018 to be massive for XB1 with the sales boost from PUBG and the release of Sea of Thieves in March.
We will know soon enough when we see January numbers:
XB1 highest January - 335k
XB1 highest February - 448k
XB1 highest March - 490k
Xb1 Jan 9th 2016 - 75k
Xb1 Jan 16th 2016 - 64k
XB1 Jan 23rd 2016- 60.8k
Xb1 Jan 30th 2016 - 71.2k