Going to share a quote from the link I posted
earlier...
This is not about being first, but to illustrate that Sony was already working on the revision in 2015, likely 2014 (as well as looking at timelines for PS5).
It is also very likely that Microsoft was also doing the same, as they too are working with AMD so there is no reason they aren't looking at the future of their market. The only difference is how long they wanted to wait, as per the hardware they seeked to sell and that may have played into seeing what Sony was going with.
It takes a lot longer to plan a product than people seem to believe. The availability of technology that can function together for a target manufacture rate is key, and why if we see a true generational leap it is very much expected to be in 2020, after the initial chips of 2019 with their incredibly small sizes start to be manufactured for iPhones and non-consumer applications.